The person who decides is dictating why the costs are what they are.
We reject user fees. The size and scope and complexity and cost of the air transportation system today is directly dictated by the commercial carriers.
There are different airplanes that require different levels of service.
User fees are costly and require a large bureaucracy to administer and are an administrative burden to companies. It's of no value.
It takes a while to introduce new planes into the system.