I don't know about how unions work at the corporate level. I can't discuss their money/reimbursement policies. However, I can talk about personal experience on the lowest level; the workers.
Anytime I have been in a place that utilizes unions, the experience has been unpleasant. Let's look a few case studies:
Case 1: Three guys all doing the "same job" for the same pay. They were forklift operators. Two of the three were slacking off, while the third one worked hard. They all got the same compensation, and the same potential for advancement. Yet one worked harder.
Case 2: A guy was always screwing things up. He was always mising up orders, etc. Yet, I heard it said several times that since he was union, it was cheaper to keep him employed than it would have been to fire him.
Case 3: A new grocery store opened up in town. For months on end, there were picketers outside: "Non-Union, don't shop". I don't know if they were getting paid by the Union or not, but either way that's a screwed up situation. Also, it didn't have any effect on the business.
So, if they weren't getting paid, they were wasting their time when they could/should have been out earning a wage. If they were getting paid, then they were being a drain financially on someone, somewhere, instead of productive citizens.
So, I am against Unions based upon all my experiences with them. They don't promote a competitive workforce where the best get promoted, instead they promote a form of socialism where the lazy can feed off the industrious.