e.g.
Correction officers’ unions are powerful forces in states like California and New York; they push for the construction of more prisons and for longer sentences for criminals (so that there are more people for correction officers to guard). Their activities in California are a case in point. In the last eight years they have spent $10 million on state politics — either in direct contributions to politicians or in spending on ballot initiatives relating to crime and punishment. They have mounted full-scale political campaigns. For instance, the California corrections union has attacked public officials, such as the Los Angeles district attorney, who supported an alternative to the union-favored “three-strikes law.” Indeed, Supreme Court Justice Anthony Kennedy in February of this year noted that “the three-strikes law sponsor is the correctional officers’ union and that is sick!” In 1999 the union even successfully opposed a proposal to permit the California attorney general to prosecute brutality in prisons.
Trying to convince me public sector unions are bad by linking me to a conservative think tank rattling off a list of things public employees fight for/against is a bad idea. I fight for/against the exact same things.
So the answer to your question is, I'm a bleeding heart pinko commie bastard, that's why. Have a glass of vodka, comrade.