I wonder if this is a bit of a Santa Monica thing? The only time I have been required to have renter's insurance was renting out of .. Santa Monica. The several FBO's there, including Justice, seemed to have similar requirements. My 'own' FBO in Az has no such requirement and assures me that I would not even be liable for the deductible unless I was negligent.
Another issue is that as a non-US resident you wonder why it's such a big deal to get a policy with your true address on it. Foreign pilots get steered (by the brokers) toward using the FBO address. This all seems very devious, the sort of thing that would invalidate car insurance in UK and even might be illegal.
After some argument with one well known broker I got a policy with my UK address on it but only mailable to me at an hotel address in Hollywood! Happily I didn't need to claim on it. The 'other' broker eventually admitted that "they don't insure foreigners".
It would be very interesting to know if the principle of 'subrogation', as is heavily larded on one broker's website, has ever been used against a renter and under what circumstances. As far as the deductible is concerned in my view that's an acceptable risk in the grand scheme of flying.