I'm paying about C$50/ year for an under-the-sink cold water inlet filter. It's not a subscription, but that's roughly how often I need to replace the filter. So $2/mo isn't that bad.
For drinking? Yes, the water stops tasting like chlorine and iron. It also filters lead, fluoride and other unvanted elements. Simple carbon filter I believe.
Not sure it makes any difference for the back yard though.
Surely their price is considerably low, but given the limited locations where people can actually get access to the water, it is not that cheap. Imagine waiting in line with your mobile phone and your cup to get a little sap. You would want a huge water tank to cut down the frequency of fetching water. Good for motorhome users though.
I believe it lacked alliteration. Should've called it Weefill. Do the Water Way with Weefill Water Waypoints, where you're in for the wettest of whistles.