I haven't played Green Hell or Long Dark. In Raft you are literally floating in water but do you know what you don't have on day one? 30 empty jars to fill up with with water that is drinkable from day one. You can inform me about Long Dark or Green Hell. Do those games allow you to load up on all the water you need for the foreseeable future from the first moments of the game? I've watched people play Long Dark and I am pretty sure your inventory is more limited than 7 Days to Die but can you build up an easily accessible stash of stack and stack of water from all that snow like you can in 7 Days to Die? I don't think so. I think you're superficially naming games that have a lot of water but don't actually allow the player to have unlimited access to it all right from the day one. I know for sure you can't with raft. Surrounded by sea water we might be but that doesn't translate to day one drinkable water surplus all around.
Getting potable water in The Long Dark isn't difficult, but it takes valuable time, consumes fire-building material, and is quite heavy. It's really more about opportunity cost than anything else; it's not difficult to do, but you have to do it, and that will impose a limit on other things you can accomplish. You could boil up a month's worth of potable water and stash it someplace, but it quickly becomes inefficient, in a game where using your time/resources wisely is basically the entire point. Plus, traversal is a different beast in TLD; it is entirely possible to spend weeks or months far away from your main base. Really great game, I highly recommend it. Very different approach than 7DTD, though.
Incidentally, you can also get drinkable water by looting toilet tanks! But those are finite, and I've never found a pistol there...