> Most of the homeless people in the Bay Area are folks who had housing there a few years before and then fell on hard times (e.g. had a medical emergency, lost a job, ...) and couldn’t afford to continue paying for housing.

These demographic numbers are often misleading. E.g. ~70% of people in San Francisco had some sort of housing in SF at some point before becoming homeless; but that number includes people who were housed through governmental programs or spent a short time on someone's couch, and a majority of this 70% had not been in San Francisco long term.

> This is politically difficult because a substantial proportion of the people who live in suburbs full of single-family houses don’t want to have apartment buildings on the same street, and cities would rather have office buildings (which bring tax revenue but require few services) than housing

It's especially difficult because when you look at true bedroom communities, they have very low sales tax revenues already, and property tax revenues are low in California, and the share given thereof to cities is small. Expecting these communities to absorb further high-service, low-tax burden is unrealistic.

The solution always is to just build more houses. That’s fine, but with that comes sewer treatment plants, power plants, water treatment (not that CA has water anyway) and digging up the existing infrastructure to expand it, etc. All that has to be funded with bonds that will have shitty ratings since there is no tax base to pay them off.

You can house all the homeless, and more will take their place on the streets.