Consider the following scenario.
A group of five people needs to rent a car (in California) for two weeks. Four people live outside the US (they came on a B1/B2 visa) and the fifth (temporarily) lives in the US (on an F1 visa). Two people (from those on B1/B2) are going to take turns driving. They are over 30 y.o. and have licenses from their country as well as IDPs. Let's call them A and B. The fifth person (the one on F1) is 24 y.o. and has only a license from their country of citizenship. Call this person C.
Assume that the drivers want to get full insurance. As far as I can see, many aggregator websites require US (or at least Canadian) credit card if one wants to purchase some insurance together with the booking. Of course, Person A and Person B don't have US credit cards. Person C does.
I see two options for renting a car:
Person A makes a car reservation on their name (with B being a second driver), presumably without the insurance since they don't have a US credit card, and then they get charged at the counter some unknown sum of money for the insurance as well.
Person C makes a reservation in their name (with A and B being secondary drivers). They can purchase insurance at the time of booking, and the insurance they purchase need not cover everything, as they will be paying with a card like Chase Sapphire Preferred, which already includes a primary CDW.
Above, I'm assuming that if the rental contract is signed by a person X, then the payment must be made by X's credit card.
(Are my descriptions correct? I may misunderstand something.)
So the question is which option would be cheaper. (If it's neither of the above, feel free to share other options.) I don't know how to compare the prices because in option 1 I'm not sure how much Person A will be charged for insurance. Also, not all aggregator websites have the option "the driver is under 25", and for some that do have it, it doesn't reflect on the price.