If it's about nowhere to shit, why did you and I not shit in the streets when we were in SF?

You're overemphasizing the secondary problem. The primary problem is that the "social services" system which is supposed to rehabilitate people who end up on the bottom is profoundly dysfunctional.

There are two groups: the addicts and treatable mentally ill, and the mentally ill for whom treatment on an outpatient basis is ineffective. For the first group, social services needs to be re-oriented away from "affirming the person no matter what" to "having the person learn the behaviors required to live in less squalid conditions as a requisite of receiving benefits". For the second group, we need to accept that involuntary institutionalization is an unfortunate and sad necessity for these people, preferable to them imposing their unacceptable (and far too often dangerous) lifestyles upon the broader population. Them wandering the streets is not helpful for them any more than it is for the rest of us living and working around them.