1. Hertz’s Tesla fleet certainly is not used solely for Uber. In some areas they are popular for regular car rentals. I know, because I’ve gotten them when renting cars on trips with Hertz.

2. Hertz’s issue is that they bought (some of) their Teslas and then Tesla dropped the price of new vehicles significantly. So even if Hertz never rented them out and had them in a showroom, they already have lost money on resale value.

https://jalopnik.com/hertz-tesla-rental-fleet-costs-deprecia...