I'm not sure about the situation in California but I looked into how taxis were insured in Maryland and it turns out they basically don't have insurance. They are only required to have a certain amount of cash in an account that acts like insurance if something happens. I believe the amount was around $30,000 which is very very little if something legitimately serious were to happen. Which is why I find it funny when people think taxis are some how better insured than ride share services.