Hollywood Unions

Alex Tabarrok looks at the question: “Why are unions so powerful in the entertainment industry when unions are generally weak and in decline in most other sectors of the economy?”

He asks his brother, a movie producer, and quotes him thus:

…unlike in most other unionized industries, it’s the INDIVIDUAL members of the unions in the entertainment industry that the management / owners want to work with. For example, Tom Cruise is a member of SAG, (I use him as an obvious example, but every other known actor is as well) and if the studios and producers want to make a film with Mr Cruise, and we all do, we have to come to terms with SAG. Similarly, Steven Spielberg is a member of the DGA, same issue. Though writers are not household names, it’s the same issue, there are specific individuals who the studios want to be writing their TV shows and screenplays. It doesn’t matter if Joe or John or Mary is stacking the boxes, flipping the burgers or ringing the cash registers so management can easily hire a non-union member to do the same job, in the film business we need to work with specific individuals who happen to be union members. Thus the power of those (comparatively) few empowers them all.

To me, this answer is missing something. Tom Cruise, presumably, knows that the studios want to work with him, and view most of the rest of the cast as interchangeable hired help. So why should he be part of the union? If he quits, the studios can hire him directly, and hire a bunch of non-union members as backup actors, grips, screen writers (given the implausibility of many Tom Cruise vehicles, do they even use screen writers on most of his movies these days?), etc. That leaves a lot more money for the studios and Tom Cruise to split up, doesn’t it? (Tabarrok feels that “big names don’t lose much from unions” – is this true if the lesser names are interchangeable?)

So why are unions so powerful in Hollywood, that even Tom Cruise and Steven Spielberg remained members?