I'm not a union guy, but I'm sure there are places where a union is needed and in some cases preferred. Funny enough, the place where I worked as a copy editor, had its workers try to go union a few years after I left. It didn't work.
Side union story: My one co-worker at my copy editor workplace once told me that his old man had worked at a plant that was unionized, and he said the union and management got along pretty well. However, when the plant started hiring younger workers, those workers wanted the same pay/benefits as the people that put in their time at that place. Then all hell broke loose or something...