Indeed- until last fall I hadn’t owned a car in 15 years, so I’d rely on Amex being primary for collision but always purchased the rental company’s liability coverage (which unfortunately really does add up). Over the years I explored, more than once, a non-owner policy through State Farm (who does my homeowner’s insurance), but was always quoted an annual premium of $700-900 which didn’t make it worth it based on my rental patterns.