They also have banned plastic bags for 2 years. I had a better solution killing two birds with one stone. Pay the bums to pick up the plastic bags.
SF has a nice plaza and lawn in front of City Hall, a beautiful building. Usually there are 1-2 dozen bums sleeping on it. When it rains, they go into the Main Library, which is on the Plaza. I have to look up info in the library when i have a job in SF. IT stinks so bad that you have to breathe through your mouth. The bathrooms are worse. I found out that the basement one, next to the cafe is ignored by the bums. I use that one when I have to.