Why are Stop Lines (in the US, at least) often set too far back to see any crossing traffic?

I see it a lot where there shouldn’t be any pedestrian activity.
This is a carbrained perspective. If an intersection is designed for cars to the exclusion of other uses, then others are unlikely to use it, which perpetuates car dependency. Even if all cars were electrified, car dependency would still be a massive problem in the US.
- I guess my thought process is if they placed the line a tad further forward where you can see crossing traffic, including pedestrians, more people would actually stop at the designated spot. The way I see it most often now is people ignore the line completely (boy who cried wolf effect maybe), further endangering pedestrians.
  
  Regulatory measures shouldn't be relaxed because people aren't following them, they should be enforced better. Of course how to do that in many situations such as this is the question. Other things are similar, like group speeding or smart phone use while driving.

Others had pointed the reasons, I wanted to add that you have to stop at the line, and if something obstructs your sight (at stop signs, not traffic lights) you have to go a bit forward and stop again.
- Speaking of obstructing your sight, I’ve been test driving a lot bc I’m looking for my midlife crisis car rn. I’ve never had a shorter car before and I’m looking at maybe a Porsche rn which sits low.
  The amount of bushes placed where you need to see oncoming traffic is stupid. Also all the blackout tinted windows that keep you from seeing traffic in front. I’m second guessing owning a shorter car
  
  Another thing i have noticed since the increase in popularity of SUVs and larger Utes ('truck' for americans) is that their body is higher as well so often sedans and small cars cant see through other cars windows for traffic stopping ahead of the car infront of you or oncoming traffic when trying to turn out onto a road.
  
  Pick up a Toyota Land Cruiser instead?
  
  That's a good thing in a way because it'd mean if you adhere to road rules, then you'd have to crawl extra slow and stop more often around these areas, and Porsche etc drivers are the ones specifically where that is often a necessity due to how difficult their cars can be to spot.

For stoplights, the stop line being comically far back is often so buses and trucks have room to make a big turn without colliding with your vehicle. If you're at an intersection where the stop line is in an absurd place, it's usually better to stop there rather than stopping wherever and running the risk of finding out why it is that you were supposed to stop way back.
For stop signs, I have no idea. Maybe it means the traffic engineer was drunk that day or something; IDK.
- There is an intersection on the south side of providence RI that is like this and every single day someone is way out there like they supposed to stop up with the other two lanes and they end up trying to back up into a line of stopped cars while a city bus honks at them
  
  Now that you mention it, even if you stop at the stop line, it's still very possible to not see any crossing traffic and then start creeping forward only for a bus to appear. By then it's too late.
- I live in a very hard to navigate city by tractor trailer in the U.S. This is correct even in the case of stop signs. Tight turns need clearance for large vehicles or else you get no infrastructure
- The lines at intersections with traffic lights make sense to me, especially since they all have crosswalks, etc. in my area.

At a guess, these are for pedestrian crossings. The idea is that you come to a stop before the line, then push out to where you can see cross traffic, then go. Shouldn’t cost more than a couple seconds and is way better than charging right up through where pedestrians might reasonably step out before looking both ways.
And yeah, sometimes these are in places where you might not expect pedestrians, but that doesn’t mean there won’t be pedestrians. Especially in the US where infra is terrible. Moreover, these things are often governed by regulations that hold for all intersections rather than having different rules for different roads depending on whether you think pedestrians are likely to be there or not.
In fact, I’d argue that the fact that you don’t expect a pedestrian to be at a certain intersection is a good reason to have more regulations to encourage drivers to watch out for pedestrians, not less.
- This answer is spot on. I know this varies by state but in my state every intersection is legally a crosswalk, regardless of markings, and drivers are required to stop at them and yield right of way to pedestrians. This applies whether the pedestrians are in the crosswalk or appear to be attempting to enter the crosswalk. The area legally designated as crosswalk is the space between the stop sign and the road, and in the vast majority of cases in suburban areas is unmarked. There is no way in most of these that a driver will be able to see pedestrians or cyclists coming, especially from the right, unless they stop at that stop sign. The correct procedure is to stop at the sign, determine that the pedestrian way is clear, and then pull forward to the road. There's almost 1 pedestrian death an hour in the US and most of these deaths are avoidable from the driver's point of view just by following this and other legally mandated procedures.

It's often intentional to obstruct vision, since it's the only real way of making drivers actually slow down. Even someone willing to run a stop sign isn't willing to drive at speed into an intersection they can't fully see.
That doesn't really require placing the line further back, but it may have been part of the motivation, along with what the others said.

They are set that far back so that you don't obstruct traffic on your right from making a left turn to your oncoming lane. You would be able to see such traffic from the stop bar.
Once you see that area is clear, you can pull forward.
It is particularly important for bikes and motorcycles to obey these stop bars. When stopped just past the bar, on the left side of the lane, a moyorcyclist is hidden behind the fat A-pillar and/or side mirror of most modern cars.
- It's also for semi trucks. They make massively wide turns to the point I've even had to back up to give them more room despite stopping before the line.
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  It is particularly important for bikes and motorcycles to obey these stop bars.
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To allow articulated lorries and buses to make a left turn onto your street.
You stay behind the line when the light is red to leave them space, then you pull forward into the junction when you have right of way.
- Yield line further forward works fine in other countries though

In the US, more often than not, intersections like this were designed to handle traffic consisting of tractor-trailers. Tractor-trailers need considerably more space to maneuver than a small passenger car or pickup truck.
As for the visual obstructions, my guess is some city planner failed to take the sight line of small cars into account when decorating or road side maintenance had been put off, allowing foliage to grow where it shouldn’t.
What you’re supposed to do is fully stop at the line and then slowly scoot forward to where you can see crossing traffic and come to a full stop again. Then proceed according to whatever traffic rule governs that intersection.

Because each state has different regulations for what’s acceptable for road design, and a lot of them are lousy.
My favorite trend is the “right turn on ramp” where you’re angled in such a way that you can’t turn your head far enough to see oncoming traffic, and you can’t see it in your rear view mirrors either. And if you are sideswiped or rear ended, you’re going to break your neck from straining to see if the coast is clear.
- Around me in these situations there's usually a lane dedicated to the merging traffic. So like turning right onto a ramp to get on the interstate, you stay in your lane without risk of getting sideswiped, then once you're up to speed it merges with the interstate traffic. Is that not the case for you?
  
  We have some of those, but that’s not what I’m referring to. We also have these right turn lanes that curve off at the intersection, but don’t have a parallel ramp to get up to speed. They just throw you into oncoming traffic. It’s dumb.
- Can you link to a satellite view or diagram of what you're talking about? The description sounds strange.
- If you can’t turn your head far enough to see the blind spot not covered by your mirrors, you should not be driving.
  
  I think he's explaining Florida merges where the oncoming ramp is about 35 degrees from the HWY, where turning up and back is too far and the rear view mirror will show you the ramp, not oncoming traffic until you're in a 100ft merge lane.
- Your mirrors are set wrong then.
  
  No there's literally no angle you can set your mirrors and still see. And if you find an angle you can see at that mirror will be useless 99% of the time you're driving

In UK it is compulsory to stop at the line, and then you start edging forward. So logically it's further back so that instead of wildly driving into a main road you creep into it. The stop line slows traffic all the way down so they're driving out into that road at 10 mph perhaps.
- This is also how it is in America, but a lot of people get pissy with you for “stopping” in the sidewalk even in the right turn lane (I assume left for y’all)
- I'm the UK the stop lines are not set back 15ft from the intersection. I don't really understand your point, or certainly how it is relevant to the question, which is effectively "why are American stop lines different from British stop lines".

I know in some places, like Texas, they seem to presume that you have a tall truck. Anyone with even a normal-height vehicle is thereby put at a severe disadvantage, especially when you try to see past the tall truck that has pulled way far FORWARD past the line, just to stop at a red light.
i.e., it is for measuring the size of one's dick, even (especially?) for women drivers. Learn to swing it proud, or else never get anywhere in those places!

I don't think it's that they're so far back, it's just that no one does any upkeep on the corners of those intersections/turns.
For instance in my city there are plenty of stop signs on corners where there may be a large overgrown bush blocking the view of traffic (or even the sidewalk, if there is one) or something like that. Sometimes it's just genuinely set up terribly.
Usually it's just upkeep and maintenance not being kept up with.
- I've driven a lot in the US (around a dozen different states) and Europe (most of the western continent), they are way further back in the US. As far as I can tell, this is because visibility in junctions is generally much better in the US. Also, the lack of roundabouts is frustrating, but right on red is awesome.

If I had to guess, it's likely a weirdly written local ordinance... maybe something that had good intent, like ensuring room for crosswalks, but it's being applied in scenarios that don't make sense or weren't considered when the rule was written strictly for compliance reasons. It's definitely something that varies by city/town.

I think it really depends upon where you live, in my area we don’t really have a problem with trees or bushes at the corners. We usually have a bigger problem with large vehicles parking too close to the corner. Making it impossible to see around them.
Depending on how big the vehicle is it how wide it is I can be a fair amount into the intersection before I can see down the road. Which is really stupid. If you have a large vehicle don’t park at the corner. This also goes for parking lots, if you have a large vehicle do not park in the end spot as you make it impossible to see around you and you’re going to cause an accident.
I live in Minnesota by the way. We don’t really have a problem with bushes trees or hedges at the corners.

A lot of times that's where people cross the street. Want people to stop before the spot people might step out into.

You're supposed to stop behind the line and then ease forward.
- IIRC in the US this depends on the state, in some states you can go straight past the stop line if you don't see any pedestrians on approach.

Death=money=thriving economy.
Sorry fo the shitty answer.