Perhaps not. But that presupposes that the American worker, post WW2, wasn't industrious enough to get by without collective bargaining.
Still, you make a good point and I'm not disagreeing that unions did serve a purpose -- during a specific era.
Currently though, I'm more than a little suspicious of Unions and their motives. Here's some statistics from Linda Chavez's book about Unions:
10% of Private sector employees are Union
40% of Public sector employees are Union
50% of Union membership nationwide are public sector employees
I can deduce from that Unions have a stranglehold on Government jobs and that their weight in the competitive private sector is pretty much nil, in 2005. I think that's a plus because I definitely believe in one motivated individual, competing in the marketplace with their own talent above the group 'collective bargaining' practices and ethics. That's just a personal opinion though, I like to be in charge of my own destiny.