because there aren't enough of them, it's literally that simple.

Here in sweden we built just an absolute shit ton of cheapo commie block-esque apartments areas in the 60's and nowadays it's some of the best housing available IMO, it's hilariously cheap (i have seen small apartments that cost like 200 dollars per month), the apartments are perfectly fine, and the areas themselves are generally car-light and at worst just kinda boring but still fine.