Paul Graham: An alternative theory of unions.
(Pseudo-disclaimer: As usual, that article probably isn't new and likely has made the rounds everywhere, but I don't keep up with what's hot these days.)
I understand that PG is talking from an American point of view. I, on the other hand, will be talking about unions from a European point of view. In Europe, the mid twentieth century usually doesn't bring up connotations of "a golden age".
In the early 1900s, during the industrial revolution, workers were habitually exploited by corporations. There really is no other word for it. The circumstances under which people had to work were abysmal (even by American standards ;-). People working 16 hours a day for a wage that was hardly enough to buy food. Young children working. Hard physical labor with hardly any breaks.
By organizing themselves into unions, workers gradually got a stronger position, and were able to demand working conditions that were more acceptable. Back then, this went hand in hand with strong socialist and communist movements. Because of these efforts, today's working conditions are much better. IMHO, this is the real reason that unions are on the decline these days... because they have become more or less obsolete.
(Unfortunately, this has led some people to believe that unions have *always* been obsolete, and that good working conditions and rights would have eventually emerged anyway. I think this is a grave mistake.)
The US and Europe didn't develop equally in this regard. Unions and socialism were strong in Europe (and still are in some regard, although they have changed quite a bit), but not so in the US. The difference can be seen in working conditions, social security (or lack thereof), benefits, rights, etc.
When I get a job in the Netherlands, even a lousy, low-paying one, I am guaranteed to get:
...and probably some other things I forgot. ;-) This used to be better a few decades ago (say, the 70s); politicians have been steadily chipping away at it since. Still, it's a hell of lot better than what you get in the US. Of course there are American jobs that give you this and more, but the average job doesn't, and somebody flipping burgers or waiting tables is so far away from these things, it's not even funny. (I think a worker bee job at McDonald's doesn't give you *any* of the above.)
As such, I don't think that unions were an "aberration"... they were there for a very good reason, and if the US had had more people willing to fight for worker's rights, working conditions would be better there also... because in Europe these are considered *rights*, not just something to lure high-profile specialists with.
Whether unions still have a reason to exist, is something else. Maybe they are actually becoming increasingly useful again, as worker's rights are on the wane in Europe.