I think it is well understood in economic theory that when you can prevent competition in the marketplace, you can charge significantly more for for your product/service. After all, if the people making 1/3 the amount the union workers were making were allowed to take the jobs in the auto industry, they would. Who wouldn't want to triple their income by simply changing employers?
However, I'm not sure that is the same as the "rising tide lifting all boats" that we're discussing here. The results seen in your example are limited to the lucky handful who have gained market protectionism from the rest of the people in the industry.