There is a pretty big upfront cost involved in charging for parking. Gates, and vending/pay machines have to be licensed and installed. Extra workers to monitor the exit gates will be needed.

We have a mall here in LA (Century City) that has paid parking. It's a mess. I avoid the mall because of the paid parking even though there is free validation from the movie theater and stores. You still have to wait in lines, insert a voucher, wait for the gate, etc. And if you have to pay, you have to go to the vending machine to get the pay voucher for the gate. It's a mess.

I have no doubt Caesars will follow-- and so will everyone else. It's only a matter of time... but maybe just a few weeks or months.