Personally I’d like to understand how other developed economies solve the many problems underlying the US’s homeless situation. Money alone will not solve mental health issues, addiction, etc.
EDIT: Yes healthcare, but especially for mental health and addiction. Solving these is pretty far beyond simply implementing medicare for all
Housing supply is a factor. I haven't managed to read it, but I think the title says plenty about one of the ways America is different from other countries:
Another significant factor is health care. Most developed countries have better coverage for their people than we do.
We are also the only developed country in the world without a good national maternity leave policy.
We are also very car dependent. In the US, housing is the single biggest expense for most people and their car is their second biggest expense. It's hard to live without a car in the US. I've done it for more than a decade, but I do freelance work. Trying to hold down a normal job without a car is tough in most places in the US because we don't have walkable neighborhoods and we don't have good public transit.
It's much easier to live without a car in many other countries. This helps make life affordable for people with jobs that don't pay that well. They can support themselves because they can get to work without a car, whereas carless Americans have trouble getting a job at all.
One significant factor is free or low-cost healthcare. Medical bankruptcy is the single largest type of bankruptcy in America, even among people with insurance, and bankruptcy can lead to homelessness. Untreated mental illness is also huge, and that's related to availability of care as well. Losing a job and then losing employer-sponsored health insurance is another version: COBRA coverage is very expensive and temporary, so people with chronic or expensive conditions may fall behind on rent etc between the one-two punch of loss of income and loss of insurance.
Why would you use COBRA as long as the ACA is sputtering along?
Also, when people frame untreated mental illness as a financial matter, it seems silly to me. Drugs are generally cheap, and the expensive ones aren't proven to work significantly better. Expensive treatments for mental illness are just a matter of exploiting desperate people because the first-line approaches don't work or are otherwise intolerable.
Sure, you can pay more to social workers and therapists, but I don't take seriously the idea you can talk someone out of mania, psychosis, or addiction.
You can fund basic research, but that's not something that can solve any societal problems tomorrow.
EDIT: Yes healthcare, but especially for mental health and addiction. Solving these is pretty far beyond simply implementing medicare for all