Square dancing should pay for it? Why do we still charge for it here? It means they spent more than 2,000 dollars on the stereo.

This is not a rule. Spent more than 2,000 to buy, let you pay, this is the same with a lot of schools run the air conditioning but let you pay air conditioning user fees the same reason. There is no such thing as a free lunch, and some people won't let you enjoy it for free, so there is nothing you can do about it, either compromise or rebel against non-compliance, depending on what outcome you want.