I almost asked my wife to write this post.
Unions can at times be useful I suppose, but they can also be like a pack of rats. I've had the displeasure of observing my wife's teacher's union for a couple of decades. They take your dues and promote politics and politicians that you may strongly oppose. If you're not a member of the faithful, they ignore or harass you. And when you finally need them, they may fail to defend your interests, due to a pecking order - in my wife's case, because the union rep. was an underling of a lousy principal that my wife was having problems with. She made several complaints to the union, which did nothing. When a meeting was finally arranged, my wife asked me to come to defend her, which I happily did. The union rep was utterly useless and threatened to throw me out.
Afterwards, my wife did her own research and finally figured out how to withdraw from the union, and they've been rude to her ever since. It turned out to be quite the caste system.
If I had to use one word to describe the teacher's union, it would be "bully." And I have a perfect loathing for bullies.