Unions are the entire reason that we have the minimum wage, sick days, work holidays, no child labor, etc... Not to even mention that our economy was booming under high union participation.
Of course, you would sacrifice all these things for the sake of the "free market."
Our economy was booming when we had no international competition, and that was when union bargaining power was its highest. In the modern global economy, US unions have bargained themselves out of the labor market. First they were disgraced by the Japanese, then undermined by NAFTA, and finally killed by China, only to be saved by TARP and other bailout funding.
They've made fools of themselves, and we have no way of knowing precisely how many manufacturing jobs were unnecessarily lost. Furthermore, most the federal government now manages pension, legacy healthcare, unemployment, disability, etc for everyone. Unions are relatively pointless. Workers have a right to join them if they please, but closed-shop laws are just lingering evidence of our post-WWII hubris.