Well, can my response to that question (Why isn’t SF preventing this?) be answered with another question like "Why Isn’t SF preventing homeless people from living literally on our sidewalks and shooting drugs out in the open? (rewind sounds of crickets cassette)
And, Dude, if you want us to take you seriously lose the red hair…
http://www.sfexaminer.com/major-victory-fraudulent-eviction-begs-460k-question-isnt-sf-preventing/