Why am I required to have a credit card to add my spouse as an emergency driver on the rented vehicle, when this has never been an issue before? Seems a bit sus.

We have a joint account and were both present. I'd have happily added my debit to the account but we were told that it MUST SPECIFICALLY be a credit card.

My fiancee and I get car Rentals alot when we travel out of town and it happens to us alot because one reason being is if you are both not there together when paying for the rental then the only one they will allow to get it is the person who is there to pay for it, another reason could be if you both are not on the credit card then only the person whose name is on the card can sign for it then can add the other person on at their request