Just for the record, Dakeese.
I think more and more as games get in to procedural stuff... For example we had to do a couple projects lately where the "generated images" as you describe were done by really generating them on the fly - I mean painting them on the fly, using code. I suppose you would say a "light AI" approach.
(So in your top example you might paint the correct grey shape, then add the darker mottling randomly, then the software would understand the "edge" and you might have say 25 random plants and the software would paint those in, perhaps add a random tree and some rocks, and so on.)
I have no idea if that is what is done in the examples you give, or, if as you say it is "just" old-fashioned fooling around with tilemaps. But there's a possibility it's not tilemaps at all, but rather they have moved over to let's say "generated painting".