When a corporation extracts surplus value from a laborer so the company gets its dues (so the execs can get a yacht) it's good
When a union extracts some dues from laborers to be able to organize the union and payout partial wages during a strike giving workers a sliver of power with which to negotiate with for a more fair share of the profits taken by those same execs (or more reasonable working conditions) it's bad.
When a union extracts some dues from laborers to be able to organize the union and payout partial wages during a strike giving workers a sliver of power with which to negotiate with for a more fair share of the profits taken by those same execs (or more reasonable working conditions) it's bad.