I work union, but my union is an old time skilled trade - printer's unions don't usually make any more per hour than non-union, and we can lose our card for poor performance.
I had to apprentice for 5 years, and take a test, to get my card, and although I'd personally prefer to not work for a union shop, I certainly don't see our specific union doing any harm to american labor. What drove our business overseas is cheap ink and paper, because here the greenies have driven lumber prices through the roof and ink production is killed by EPA regs.
While unions in general have become a greedy political machine, no one should EVER forget what working conditions were like for most people before the Unions came to be, and how good things are because of their efforts. People like to assume because unions are corrupt that they serve no function, or worse, that business without a counterbalance will be benevolent or good for the working class. That's very small-minded, if you've read your history you'll understand why.
Like most things nowadays, it's become a polarized, complex fight and people either believe unions are good or evil, when in truth it's neither. They are no more completely worthless than business is completely good.