This is only an issue for a few kinds of rental vehicles, and I doubt that will be the case for much longer. Teslas work just fine when out of cell range, as they unlock using your phone's bluetooth or an NFC card. If the car is in cell range, you can lock/unlock it remotely using an app on your phone.
I get the impression parent comment is less concerned about pragmatism and more focused on “freedom of choice”. An EV converted Land Rover would be awesome