I always wondered how it would work in a rental setting. I used to work in Insurance and OK I am going back a long time when I started but vehicles were categorised and a major factor would be performance. Pretty much any Tesla would outperform even the flashiest sports car of that era. Repairability is another factor, Thatcham did that for the UK. Plus of course location, driver age etc etc.
You simply did not get Rental companies using very high performance vehicles.
Judging from that article it sounds like they intend to detune the vehicles, which I presume is a software fix, lock the vehicle into Hertz mode.
I do not think repair costs will be different GM vs Tesla, the Legacy Manufacturers are moving in the Tesla direction.
I watched something recently and this involved a Ford ICE but amazing how much information Ford, and presumably Hertz etc, can collect. I can see that being a cost factor when renting a vehicle. Or insuring one.