This was actually done in the FR, with regional human feats in FRCS. Humans from Lantan could take a feat that gave them cantrips, because it was a really "magical" area. Humans from certain areas could take a feat that gave resistance to disease (those areas had been hit by a plague), and maybe from one area could take a feat to give resistance to cold environmental conditions. (That's even weaker than resist cold 5 though, so I wonder if anyone ever took those feats.) Alternatively, D&DN-style backgrounds could cover this sort of thing. A "woodsman" background doesn't sound very urban. A "city rat" background doesn't sound very rural. But most PCs are likely to take backgrounds like "soldier", "noble" or "scholar" instead. These have their own implications. (Nobles are pretty much both urban and rural, having country estates and spending time in their local capital.)