I feel the problem is rather in lack of competition. Even if there are 2 or 3 handling firms at the airport, they can set the prices by mutual agreement. Not legal, but real. To create a fourth company and compete with them does not make economical sense. No real competition is possible.
If there would be a second airport competing with the first one the situation would be different. Both airport managers would pay attention if the handlers at their airport attract or repel the customers. This would set the prices at the level of lowest possible cost + appropriate profit.
But a second airport is not there because there are too many regulations, planning permits, noise abatement...
The market forces are not allowed to work.
I did my night rating in April. Landed in Bratislava (LZIB) in the C172, in the dark, no traffic, deserted airport. Departed an hour later after paying 57€ for landing and 400m ride in a bus. There is mandatory handling and only 1 handling agency. State owned, government run airport of course.
You can track every such anomaly and find the government idiocy at the end.
Miroc