In Hawaii lots of people live on the beach, and don't get hassled for it. (Maybe they do get hassled, but anyway it isn't enough to end the practice...) There probably should be some sort of freely available liminal space in other states to serve the same purpose. Actually it seems like some people live under bridges?

300 million people can't do this. By and large, save for very few people, we all have to participate in the housing market. There are also long term, detrimental effects of having a large percentage of the population living on beaches or other designated areas.