It is a private organization, with private workers (players)
The boss sets the wage, if you won't do it for that wage, you should look elsewhere for employement.
If the boss (owner/ CEO etc) is making huge profits while paying peanuts (percentage wise) to their workers, the workers should think about looking for new work.
If players refuse to play for those wages, no game takes place, no game = no tickets= no money for the owner.
If the owner thinks he can recruit quality replacements that people will pay (the same amount) to watch-- then the boss will likely try to fill the slots. If not, the boss will need to negotiate with the skilled workers an agreed upon wage. They need each other- No owner= no stadium. No players = no revenue.
So- No I don't believe in salary caps. Your qualities and what you bring to the table determine what you make.
When you see 6 and 7 figure incomes, it is easy to say "they make enough" -- but in reality who am I to say you make too much. If I think you charge too much for your product, I will not buy it.