Holly-Guild??

In reading another blog, I ran across an interesting article by Tyler Cowen. I had never really thought about the issue, but it made me ponder. Why are there so many unions in Hollywood? What makes the varying guilds in Hollywood so prevalent and able to succeed vs. that of other sectors?

Tyler cites the goals of unions and guilds in Hollywood as follows:

Additional important functions of the unions and guilds are (a) the codification and regulation of professional categories, (b) accreditation of members' work experiences, and (c) the provision of educational, labor-training, and other qualification-enhancing services.

Almost every person in Hollywood belongs to some kind of guild or group, from the actors, writers, directors, location managers, all the way to set electricians. With one of the main goals of unions as defined in various economic books being providing safe working environment for the members and better pay/benefits, it causes one to wonder. Do actors who make 15 million a film and have stunt doubles really need to belong to group with the power to argue for them? Perhaps some of the 'overlooked' behind the scenes people that aren't making gross amounts of money, I could see the point of pension plans and such. And generally the fees one would pay to a union would go to what is deemed at a 'strike fund', well movies are always produced, so if one actor walks out, for 15 million, someone else would take the place. Now for writers and other such varying positions, I could see the need for benefits and no exploitation of the work they perform.

What are some thoughts on this?