Where are you allowed to sleep for free in the US? You could perhaps get a wilderness permit and live in a national park for a time, but I'm not sure what the maximum period of validity is on them. Cities will cite you under anti-camping rules. There isn't really a frontier to go to where a person can live off the land, at least so far as I'm aware.
People who do not find the system of "I have to work because I have to have money because I have to pay rent/own a home because I have to have somewhere to sleep" satisfactory no longer have a frontier to which they can escape. This is worrying if you like the idea of preserving liberty, and especially worrying if (as this article suggest) the whole monetary system on which our civilization is built rests on weak foundations.
At least prison's still more or less free.
http://www.alternet.org/civil-liberties/us-laws-criminalizin...
https://www.landcentury.com/under-1000-land-deals/
Though some local governments will go after you for zoning violations, check first.
And so will the wealthy foreigner--with a lousy phone call.
I've given up on more building. I think we need to open up areas where people can camp without breaking the law. Or, at least allow people to legally sleep in their vehicles. The fines/fees for breaking over stringent municipal laws are just not fair.
(I don't believe lightening up municipal laws will cause the average person to sleep on the sidewalk to save money. Yes, we will always have homelessness. I have known two people who were between rentals, and were ticketed for sleeping in their cars. It's just not--what's the word--the America I thought I was proud of.)