I don't live in SF, but homeless shelters are oftentimes disgusting and terrible places. I don't blame anyone that doesn't want to stay in them if they can figure out other accommodations. Nonreligious based shelters sometimes provide very little in terms of hygiene/necessities/food, sometimes basically nothing other than a small cot or gym mat (aka no food, no shower, etc).
Religious shelters often require religious involvement. Forced praying as an example.
There is also the issue of frequent abuse/sexual assault in homeless shelters.
> Being homeless or poor is only an excuse for stealing if you cannot reasonably get your basic needs met in a legal way.
I don't really think shoplifting food to survive is an "excuse". Again, they're not stealing CD players.