There's situations where they make sense to rent and vice versa.
Business traveler who just needs to go between the hotel and the airport? Great; may not even need to charge.
If I'm flying into Vegas to do a roadtrip to the Mighty 5? Nope.
Rental companies already have lots of different categories, so it's fine to have a mixed fleet. Just requires some extra infrastructure and consumer education. Which, I know, is in short supply, but can be done.