Hotels do also, based on nationality. I’ve had to implement something like this when working at a hotel aggregator (like Trivago but not them). You would start the booking process from let’s say Germany, but you have a Romanian passport. You would get German-people prices (which are lower) based on your IP, but you were asked about your travel documents. We had to do a request with your password to the seller which would reply that the room was already booked. You would get a message to start the search again, but now we would do it with your actual data. You would either get the room listed again at a higher price or not at all.