"Mayors in cities or towns with a Mayor/Council form of government are required to prepare, and submit a budget to the council for approval on or before Dec 1 of each year."
It also states within that the Mayor is responsible through the budget to set the salaries of the Executives, and Council.
Now, the obvious thing here is that each dept. within the municipality submit their budgets to the executive, and the executive submits it for approval through the council.
Are we on the same page so far?
Now, If you have a union negotiating the salaries of the people working within that framework, then they are also voters of the executive, and council, right? So, it is an unfair advantage because as the union becomes more powerful, they hold a voting block over the Mayor's, or council's heads, and therefore, it is a corrupt system.