Sounds more like a political party than a labor union.
I expect this will be a big issue in tech unions also.
[0] https://www.detroitnews.com/story/opinion/2019/10/16/opinion...
Union shop, not closed shop. Closed shops have been illegal for over 70 years.
In the US, outside of states with right-to-work laws, a union shop can still require workers to pay dues even if they aren't members of the union.