Not necessarily, folks are incentivied to keep the cars clean and undamaged.

Cosmetically maybe, but Hertz has very good incentives to do minimal maintenance and only fix things when very broken. The renter has little incentive to report issues like weird noises or anything mechanically broken, especially if it may have been caused by them.

Sure but there's no incentive not to be hard on the powertrain. Probably less of a problem now with so much drive-by-wire preventing you from drag racing a Camry.