The Washington Monthly: "It's because unions are the only truly effective check on the sine qua non of modern conservatism: corporate power. For all their faults — and they have plenty, just as corporations do — unions are the only organizations that have the power to bargain effectively for the interests of the middle class. Union power in the private sector began to wane in the 1970s, and it's not a coincidence that this was exactly the same time that middle class wages began to stagnate, CEO pay began to skyrocket, and income inequality began increasing inexorably.
Many liberals seem to believe that these grim trends can be fought with tax and regulatory policy, but those are blunt instruments with plenty of drawbacks and unforeseen consequences. Collective bargaining, which is essentially a market based approach in which the government's job is simply to make sure that unions have enough authority to ensure serious bargaining and then get out of the way, is far more reliable, effective, and flexible. It actually works, which is why conservatives have always hated unions so bitterly.
Despite this, there are plenty of cocktail party 'new' Democrats who blithely think of unions as just another dinosaur special interest unsuited to politics in the 21st century. They should think again. Republicans understand the stakes a lot better — and so should we."