On the ranges we have two types of employees, government and contracted. The contractors are typically electronics technicians, eletrical engineers, etc.
Things are a bit different today, but in the past this is how the system worked.
The government would allow companies to bid for the employee contract. This happened every three to five years (or so). The government gives preferential treatment to small businesses that are minority owned. Typically, at the end of a contract period, the company was no longer eligible to bid for the next contract because they became to profitable. Keep in mind... the employees never changed. They stayed on from employer to employer, but did the same work. The only thing that really changed was the administration.
So... the companies have a competitive bidding process. Wages were not allowed to decrease from one contract to the next, but benefits were being cut every time there was a new contract. Wages were seldom increased.
I was a contracted employee and we had a big push to go union. In addition to the wage issues, we had a program manager (lead contractor) that was a horrible totalitarian type. He wasn't particularly qualified to be in his position, but had managed to land the position simply by being in the right place at the right time.
I was on the union board and negotiated the collective bargaining agreement with the company. During our negotiations, a couple of things happened. The PM got fired and the IBEW provided us with current county wage determination guidelines. Many of the employees enjoyed 15-20% wage increases.
Everyone looked up and thought... we don't need the union.
They overlooked one small detail. If there was a CBA between the company and the employees any new company that came in would have to honor it. The employees would in effect have a voice in the government/contractor bidding process.
Anyway... there are still good reasons to have unions. Sometimes, unions are abusive. Same can be said for corporations.
Sorry for the wall of text.