Many (most?) credit cards have rental car coverage, it saved me a ~thousand dollars when a bird shattered a windshield. I always make sure the card I rent with has it.
I’ve seen customers get denied by their auto insurance and 2 credit cards. Just because a credit card provides coverages it doesn’t mean it covers everything. Insurance is complicated and you should never assume you are covered.
This is true, but often this only covers physical damage to the car only, not anything you hit. Claims for loss of use of the rental car while it's being repaired often aren't covered, either.