Because homelessness. Because medical bankrupcy and opioid crisis. Caused by THE SAME industry. Nobody's responsible. Because USA is designed by and for small groups of people owning the companies providing for ridiculous money at insane conditions what everywhere else is cheap or free and well regulated.
As I understand it, these folks want privacy, storage, pets, quick commutes to loved ones, and/or drugs/alcohol.
I think it'd be easy to offer privacy and storage. Let them have locks on their doors (that staff can open). Put cameras in the hallways. I think these things could be done affordably, especially if housing was built on cheap land.
Dogs might be possible and might help some of them recover. There would need to be a system to keep violet animals and maltreatment down, and sanitation would be important. Apart from that, animals help calm the mind. That's probably cheap to do too.
You'd need to feed and clothe everyone, but it needn't be expensive.
Transportation is expensive and should be offered in a limited basis. Non-profits probably already have this cornered, and you could do it at scale even cheaper.
The substance abuse problem I haven't the slightest idea on. You ideally want to get them to stop abusing, and most taxpayers would gag at the thought of providing homeless with the drugs of their choice as an incentive to get off the streets. Not sure how you compel the addicted to leave. Forcing them to leave would be illegal in most municipalities, and it feels a little wrong unless we have quantifiable data that it helps their outcomes.
And then there's the fact that each individual will fall into a range of mental health states. Some may be permanently disabled and in need of institutional housing (which I don't think we do anymore?)
It's a tough problem. Every nation has to deal with this, but some are clearly doing better.
I'm not well educated on this topic, so maybe I have the incorrect assumptions.