When I was there last week I spoke with the Resort in depth about how they'll know to charge parking. Specifically addressing people who never go to the front desk, or only had a car part of the time and Uber.
At this time it is 100% on the shoulders of the Guards. The CM at the resort even said "if the guest really wanted to, they could pretend to be doing an Uber drop off and they would get around the parking fee" Though the CM did go on to talk about some of their techniques used to determine when a car has been in the lot for an extended period of time, and not one they have associated with a guest. (chalk marks on tires).
We even talked about their license plate system and the CM said they are not using that for anything other than determining cars parked in case of something happening, in the CM's example, like a car blowing up. They are not reading plates to tell how long a vehicle is parked.
The guard is the one that is supposed to check the car as it comes in and ask if they are dropping off, checking in, dining, etc. And go from there. That way, a guest who never goes to the front desk will have their car logged and a guest who arrives in a car via Uber won't get charged.
There is 1 thing I forget to ask and that is how they will know how many nights if the guest doesn't move the car after they arrive but they also don't keep the car the entire time. Say, you arrive in a rental and drop your family off, stay 1 night and then return car next day. This may be a case of you have to straighten it out at check out. There are bound to be exceptions here and there. We are back at the end of this month and I'll ask about this specific case then.