The whole arguement about being realistic is besides the point really, since in real life you do not purchase a gate, you get slots. A certain time assigned, for which you pay. May be included in handling costs, may not be. In any event, it is not true there is a fixed amount of payment. If I had an airline and flew twice a day to Heathrow, I'd be paying for that. Now, if I would increase to three, or four, my slot expenses would increase.
The system is a lot more complex than just purchasing gates. You need licenses to be issued, you have to request the slots in advance and wait and see what is allocated to you. Don't make the mistake of thinking it is an easy matter..
I beg to disagree. Although I am sure there is an infinite number of arrangements worldwide, in the US I believe that the arrangement is:
Lease gates from the airport. These leases are assets in that you can sell, sublease, transfer or assign the gates. Or return them to the airport (anyone know what USAir did in Pittsburgh?)
In addition, there are landing fees. These factor in the plane size and number of passengers. I know there was talk about premiums for landing/TO times but I don't know if any airport has instituted that.
So far as Landing/TO slots, I am not sure that there is a fee for that outside FFA but it wouldn't surpirse me.