I have excellent health insurance by US standards (the most expensive plan offered by a big tech company in SF). I've been battling mental illness for the last two years (more like two decades, but getting treatment for two years after it became untenable), resulting in months of medical leave from work on the advice of multiple doctors. Even with "excellent" insurance, I'm approaching $50K out of pocket over the last two years. It was more than that before my insurance company decided to cover my illness and reimbursed some of what I had previously paid (after 18 months of me, my doctor, and HR fighting them). What if I wasn't lucky enough to have "excellent" health insurance and sufficient savings from years of high paying jobs? If I wasn't so lucky and ended up homeless, what chance would I have of recovering from my condition? I've avoided alcohol and drugs my entire life because I know I'm prone to addictive behavior - I'm guessing one cold night on the street would be all it would take for the first drink. It's scary to think about where it would go from there.
Healthcare for homeless people tends to be emergency rooms and under-resourced free clinics. Given my experience being treated for mental illness, I can't conceive of making any progress in free clinics or ERs. So why wouldn't I be a permanent resident of the streets?
I see talk here of homelessness being less of an issue in Europe and China... in my opinion, access to healthcare is a key difference. Treatment for homeless people is great, but how sane is a system that pushes people off a health/financial cliff before they can get such treatment? Financially feasible access to treatment long before we get there is crucial.