In the great scheme of things £1 isn't a huge amount to pay but rather than the amount charged I think it is the principle (no pun intended) behind it.
There is an argument which says that airports are there to provide a service to the travelling public. Do railway stations charge a drop off fee? The main station in Nottingham has a 20 minute drop off zone which is free. Ok different numbers but I feel there is a principle here. Do they have drop off fees at airports in France or USA? What reaction would people in those countries have to the imposition of a charge?
If they are so worried about passengers behind dropped off by road transport then why not build a railway station at the airport on the Nottingham/London line instead of the hideous Parkway station which doesn't even have a shuttle bus to the airport anymore so that you have to use a taxi.