Correlation may not imply causation, but where there is causation there usually is correlation. So, if there is a rise in homelessness there is likely some factor contributing to that and if a factor is correlated there is a good chance that it's causal. Homelessness may caused by multiple factors but if it's increasing and those factors are mostly remaining static then looking for the one that is also increasing seems like a good bet.
Having actually built, planned, and done all the paperwork for a house myself most the extra costs that can't be worked around (you can DIY everything if you want) is permitting, inspection, and codes. I just didn't get my house inspected nor did I submit engineered plans, so saved tons of money, but most people don't have the option to bypass 'safety' inspections and they get gutted like a pig following all those rules.
The actual materials cost of a house, you can build one for $60k no problem and absolute shit-tons of cheap land near jobs (ex: unemployment extremely low in the Dakotas, cheap land, high demand for homeless-tier labor in the fields in bumfucklandia as ICE deports illegals making farmers desperate for anybody).
They may be desperate to hire anybody, but not everyone is willing, with good reason, to work 16 hour days with no overtime pay and sub-minimum wage no benefits and work for only part of the year and get paid under the table. only reason it make since for migrants is the low cost/standard of living back home and currency arbitrage where us dollar are worth so much more than their own currency.
Yep, there's plenty of awful jobs with no requirements but a pulse. The problem is that they'll grind your spirit and take all of your dignity and time, if not outright scam you themselves (see: MLM).
You can enter Mexico, and they have only checked I had paperwork/passport about one times of ten. No reason why you can't do the same thing if you want to do currency arbitrage. Paraguay will give you a residence permit pretty much just for showing up if you can get ahold of a USA passport, or you can avail yourself of the compact of free association and live in Micronesia without a visa. The arbitrage game is for everybody.