Unions in the US have always seemed different than the ones in Europe and Canada (especially Quebec).
I always sensed that the US public was less supportive of unions than the European union, as demonstrated by overall levels of union representation in the workforce (much lower in the US) and general attitudes in conversation (admittedly anecdotal information).
US unions also tend to be more on top of things in negotiations. They tend to stop working as soon as a contract expires, rather than working towards a settlement for what seems like an eternity like they do in Canada (some unions will go 4 or 5 years without a contract, get a lump sum payment for the difference--but the new contract is only good for a short time before the never-ending process begins again).
And when European workers aren't happy (as they aren't feeling right now with all of the job cuts there), they take to the streets.
A Week in Review piece from the April 5 New York Times sheds some light on these differences. Read the entire article at http://www.nytimes.com/2009/04/05/weekinreview/05greenhouse.html?ref=weekinreview.