OK I admit I didn't answer anything. They'd probably bum rides off their friends with cars, just like I did as a kid. Which doesn't scale and is very inconvenient and economically devastating.

There are some interesting real estate issues such that you'd essentially be implementing feudalism where a peasant comes with the land and cannot leave it for other employment. Or the parasitic FIRE sector would have to back off a bit so housing is more of a commodity. Either way isn't happening without much unhappiness.