[cromka]

> They also don't cover damage to other cars, only to the rental vehicle itself.

But that's covered under the liability insurance, which is mandatory in most jurisdictions and included with base rental fees already. In the US it's mandatory, too, AFAIK, but the the default insurance will usually cover the minimum required by the state, so you may want to have a separate liability insurance after all with a higher coverage.

[skuhn]

I think that's the case in most US states, but it isn't provided in California.