[akira2501]

> whereas you didn't have collision coverage of your own?

That's the majority of people who don't have a lien on their title. Liability insurance covers what you do, it doesn't cover what someone does to you. So having evidence of who caused the accident is important when everyone just has liability coverage.

In California, though, I really do recommend you have the "Uninsured and Underinsured Counterparty" option on your insurance. It's usually far cheaper than the alternatives and it just covers you with no effort on your part.