It's more about hierarchical social structures than like... coercing a boss to accept a union. Like you shouldn't have one person in your group who can kick you out or make you do things if you don't want to, or no one should be forced to work a job to make ends meet, through the coercive power of wage labor.

That's not the same as like, you and your co workers getting together and saying if the boss doesn't negotiate we'll go on strike / slash his tires / what have you. That is coercive, in a way, but it's not really the same thing.