Because it's inevitable there. I have a friend who was prosecuted for self sefense in Oakland. He ended up getting off with probation, because they couldn't find the guy who attacked him and he shot. Then they found him in prison for sexual assault etc. and he had a long, long record. the prosecutor wanted to throw the book at him, but realized he didn't have a prayer given the person who was shot.
This is one of many reasons that I am leaving the country when I retire.