Once I rented a car in Seattle one way to Vancouver. Apparently there is some shitburg nobody has ever heard of called Vancouver, WA but I was going to the more famous Canadian city. The flunkie at the counter booked the domestic trip and I drove to the proper Vancouver. When I got there they tried to charge me over $8000 in fees. I think there is no practical upper bound to what they'll try to charge you for such things.