Well to be fair Unions have less power than they used to. But it seems more often or not it's a Union that serves the Public sector rather than the Private sector that strikes.
For Chick's sake. It was one day.
In America, the private sector makes more money, generally, to keep out unions. There is also a myth that public sector jobs pay more than private sector counterparts. You have to fight for what you get, and for what you've already got.