I visit SF and Silicon Valley fairly regularly from London (where I live so potentially biased). I am always, always, always shocked by the homelessness (and the mental state of those poor souls) in SF. People call London a dirty, unfriendly city but I've NEVER gotten any trouble from any of the homeless people in London apart form the usual begging, yet in SF its pretty much guaranteed you're going to get hassled/sh…
Instead you will get a vocal minority of people saying the homeless choose to live that way or that they are made homeless by rent control or public housing or excess regulation. Since this matches most American's world view, it is accepted without evidence.
It is a society that will always strive to raise housing prices not lower them, more willing to give handouts to defaulting mortgage holders than to give housing to the homeless, and more willing to jail the homeless than to house them. And so the situation worsens as it has for 30 years.
The best SF can do is put endless bandaids on a small part of a national problem.