Control?
The union and management entering into bargaining sessions, which means they collectively come to an agreement on employee management.   
If the union control's employers and taxpayers, the management is part of the problem from their lack in ability to negotiate.
Also, take a few minutes and read about the benefits of unions, ​particularly to how all employees have benefited from union demands....interesting and quite informative.
I have never been in a union but firmly believe they are valuable.