Unions aren't always antagonistic. Although the antagonistic moments invariably get most of the coverage, most of the time union and management have a cooperative, symbiotic relationship. As a manager of a company or division, I would actually want to have a worker's representative organization that could provide some kind of view into what the mood and opinion of my workers really were.
On the other hand, the credible threat of strongarm tactics, no matter how rarely used, is completely inseperate from the existence of collective bargaining. In average circumstances, one cannot have collective bargaining without authoritarianism, just as one cannot have collective action without it. The very existence of law is a testament to that; after all, we would all be better living in a well-behaved society than a poorly behaved one.
