accident ? for you California people.

We had a accident 8/9/15 west side of Tahoe. Our car an the girls truck was smashed all to hell. No police report was done. Chp passed it off to south lake Tahoe PD. The PD says they don't have to do a report as long as both party's exchange info. So now what the hell can stop my insurance from saying I caused the accident ? So do you people pay your own way and assume your 50% at fault an then your own insurance takes a big hike even though you were 0% at fault. Is this why I'm having such a bitch of a time with my own insurance progressive to get some money out of them. Why they are continuously falsifying facts to keep the money down.