I don't know why Hertz is making a big deal out of bringing the cars back charged, other than as an excuse to make some extra cash. The cars probably sit there long enough that they could plug all their Teslas into 120V outlets and charge them fully; their only expense would be a little bit higher electric bill.
Now whether they should charge them fully is another story. No higher than 80% is best for long battery life, unless they know the customer is picking up the car today, in which case 100% is fine.
The location I rented from didn't have a fast charger, and the first time I rented, my car had just been dropped off a few hours earlier and was still charging.
Setting max charge to 80% is fine, but I think it would be nice to add a paid option to start at 100%. Most folks won't need it, but for those who are road-tripping (me), it makes a difference. Happy to pay a little extra in that case.
they probably make a sizeable amount of money on people returning cars without enough gas and thats one less revenue stream if they dont do the same for charge
Now whether they should charge them fully is another story. No higher than 80% is best for long battery life, unless they know the customer is picking up the car today, in which case 100% is fine.