[InclinedPlane]

Let's say you are a tech worker in silicon valley. Your wages and the sorts of jobs you have access to are dependent on the sorts of companies in existence, their needs, and your skillset. If you have a highly sought after skillset then you will be courted by multiple companies who will try to woo you with jobs that you find desirable and competitive compensation packages. Let's say instead you are a dock worker in long beach. In that case your compensation and career opportunities are far more dependent on your union membership and seniority.

Certainly playing corporate politics can also have an effect, depending on the company, but that's also true in union shops as well.

[cdcarter]

Very few unions have a mandatory favored nations policy. If you were significantly better at dock workering, such that a company sought you out, they can easily pay you more. That being said, many union labor positions don't have a wild variety of skillsets. They often do need protection.