Murder is not the only crime. I, and a bunch of my friends, have been attacked (punched, followed home, etc) by homeless people in SF. This has never happened to any of us anywhere else, and we are a group who travels a lot to a lot of cities, including internationally. I didn't report it to the police when I was sucker punched in the stomach by a homeless guy who ran away afterwards, because I barely saw him and what would the police do? It would just be a waste of my time. Another friend was beaten so badly he had to go to the hospital, but the police did nothing after he reported it.