The streets may not be the best sample though.
There are homeless people who work and live in their cars.
Getting government and NIMBYISM out of housing policy will lead to affordable housing and is paramount to fixing this.
Opportunity Zone Investments should also help some.
The trick is getting government and nimbyism out of housing policy while getting them into drug and mental illness treatment at the same time. These days it doesn't seem like there's a political party that can handle that kind of nuance. It feels like it's either expand government on all fronts or retreat on all fronts and that's not what's needed here.
I moved away about a year and a half ago, when homeless tents were pretty common. When I visited recently, it was stunning how much worse it is. Almost every green space in the city (except for popular parks) is filled with tents. It's really crazy.
Quite frankly, given how many decades Seattle has had a significant homeless population, I'm surprised the city hasn't taken point on treatment and housing programs. They have a unique opportunity to really help a lot of people out if they'd step up and do it.