Just out of curiousity, who do you think are the militant unions? There probably are some, but doesn't mean they all have to be laballed as the same.
I'm a unionist (I'm an electrician, so a member of the Electrical Trades Union), and they make sure they do everything by the book. Unionism had a bad light a few decades back, but now they are a very proffesional run organisation, who also look after each and every member.