People don't wash or wax economy cars. At least I think that's what's going on.
At least up here in the land of harsh winters, I don't even see Chevy Cavaliers or Ford Escorts around anymore, and the few first-gen Focuses I still see on the road are rapidly turning into to brown powder. Civics and Corollas fare better, because I think they are made with better rust protection and they're a bit more bulletproof, but the turn-of-the-century jelly-bean looking Civics are still starting to disappear too.
I honestly think people just treat them as disposable, don't take care of them, and scrap them when something expensive breaks. Because when I do see an older economy car, it'll be in absolutely gorgeous shape, without a spec of rust or anything. But that's a rarity. At least along the route of my commute.
YMMV. But our weather eats cars here.
20+ y.o. midsize or large cars, 20+ y.o. trucks, SUVs, minivans, etc., those are all over the place. But people take better care of them from the get-go, IMO.