Chicken and Egg
Airport charges, whether it is FR, U2 or BA, are negotiable. That is life in our "free economy"
If any airline can agree free, or subsidised, charges I can't see the problem: no airlines, no revenue...see DSA.
If airline X is bringing A million passengers per year and airline Y is bringing A million less 900,000 do you really believe that they would receive similar discounts?
If I bring 1.2 million passengers to your airport, and the next airline brings brings 200 000, do you really think that I have no leverage? Economic reality, dear boy.