Can't speak for other games, but there's a LOT of former truck drivers who play Snow Runner.
Back when I was working as a forklift driver, when I broke my leg and was stuck at home on the sofa I really enjoyed driving the forklift around in GTA5 and just moving palettes around.
I choose to believe the only people who play Euro Train simulator are German train conductors who want to pretend to operate a train while eating pretzels and drinking a responsible amount of beer.
I work with kids who are seeking vocational education, and I can tell you that it is definitely not just office workers.
A favorite is euro truck sim 2. Weirdest case I've met though is farming sim. I've talked with 16 year olds who'd play that game for hours daily. Even got a friend of the family who'll come home from driving a tractor for 14 hours straight, and then play farming sim to wind down.
I know the farming simulator type of people. I think those people simply have a high professional interest in farming economy, management and agricultural technology.
Even more impressing than those who play every FS 20xx for hours I find those who mod for the games. Year after year they photograph, model, program and share their equipment, which is sometimes decades old.
Playing ETS2 is just something you do while listening to the radio, the long highway stretches of not having to reverse a trailer into the eye of a needle are superbly relaxing.
If you want to check out something related, wierd, and interesting check out German radio controlled truck conventions ... lots of people go together and drive their RC stuff in a sensible realistic manner. I find it adorable.
I've put a ridiculous number of hours into Ship Graveyard Simulator 2. Why am I, a white collar guy from a developed country, spending hours pretending to be a Sri Lankan with one of the worst jobs in the world? It's bizarre when you think about it.
Who am I to judge? I've played several nuclear power plant sims... But come on? Gleisbau? And a sim where you're paint stripes on roads? Go home Germany, you're drunk.
If I remember correctly those games were all pumped out by one studio in a short time. They're heaping piles of trash, sometimes literally unplayable and probably only had players because they gave them away with gaming magazines.
Yesterday I spent 1,5 hours to sort my 550 mods for a new Rimworld playthrough. Game didn't launch, so I decided to try again another day and ended up playing Guild Wars 2.