Coasthugger - I wouldn't be to concerned for the airport authorities. Have you tried to book a cheapie low cost flight lately? I have and although you might get your fares for 10 or 20 quid, there is at least 20-30 of fees added on. One Aer Lingus flight I booked for 20 euros return had just under 50 euros of fees added on. Granted only a small amount goes to the airport authorities (say £5-10) but how much do you think they should get? After all like you say they get money from landing fees, car parking, cargo handling, lease of space for offices, shops, a cut from the concessions run within the airport...the list goes on.
If you are worried about costs at airports going up then look at who runs them and if they are being run as efficiently as they could be. There is an interesting thread running about the development costs of Stansteds runway for example. See the numbers involved for laying some concrete and you start to get a feel for how the airport authorities can get away with it.