They work with the Hilton to advertise Hilton’s parking lot for long term parking. They charge a $ 12.49 fee for a «discounted» reserved stay. Parking space is not reserved, so if it is full, you lose. The pre-paid day of stay is the free day all customers always get whenever they park there. So, there’s no paid for day you wouldn’t have gotten anyway, there is no discount on the stay and your space is not reserved anyway. You’ve paid $ 12.49 for no value at all.