I find that the liability-insurance information posted on Hertz's website to be useful. It identifies the handful of states where Hertz provides liability coverage to those without other insurance and does not seek indemnification in the event of a claim under the coverage limits. (I can't imagine that Hertz would provide such coverage out of the goodness of its heart, so that coverage is probably required by state law.)

https://www.hertz.com/rentacar/reser...RAGES&EOAG=LAX

AARP members who rent from participating Avis/Budget U.S. locations using the AARP discount code get a small amount of primary coverage ($25K/$50K/$10K) at no extra charge. (Those under 50 can join AARP as "Associate" members.)

If you rent cars with sufficient frequency, a non-owned-auto liability policy might be cost effective. Mine is issued by Travelers Insurance.