Most valet operations are contracted, so only the contracted company MAY get paid by the casino or they may have to pay the casino to operate much like a stylist/barber pays the salon or shop for booth space. I would image that valets out there get paid at least a minimum wage (not sure if it would be the normal or "regularly tipped employee" rate) by the valet operator.

Of course a valet (and other people in the service industry) in a "flash and trash" capitol have more opportunity to make large money because people tend to throw money around to impress others. You don't work at that level of the service industry in "fly over" land if you want to become rich, it's something you do to get by until you figure out what you want to do when you grow up. If you want to make a career of it you need to be on the coasts or Vegas.