I can only think of extremely land-limited places like Monaco and Gibraltar. Where the answer is "not everybody should live in Gibraltar".
But the US has a lot of land. So much land that it can afford wasting it on endless sprawl of single family homes, which is the least efficient way of providing housing. Most Asian megacities would not be able to exist if they had as strict zoning principles as the US has.
Maybe you should also think about barriers such as "bans on boarding houses". This is what messes with poor people the most. A room in a house full of rowdy individuals sucks, but it is still a room. Possibly you may spend just a year there, then find something better. A tent in an encampment of rowdy individuals is strictly worse on all accounts except cost, and bouncing back from that is harder.