Unions can go either way. They suffer from the same problems as democratic governments, ie prone to corruption and bloating and working against the people they are supposed to protect.

What do you do in that situation? Do you have a Union for you Union?

Just a few days ago, this was trending on HackerNews: https://news.ycombinator.com/item?id=36188406

Police unions who are paid by tax payers so they would enforce laws written by people appointed by people, make their own buddy clubs and pick and choose the enforcement.