[rverghes]

It's generally to prevent free-riding. Let's say the union negotiates benefit X, and the company then provides benefit X to all employees including non-union employees. An example could be safety features that the union is pushing for. The non-union employees have benefited from the actions of the union without having to pay the cost.

To balance this, involuntary unionization usually requires a majority vote from the employees to unionize.

[blisterpeanuts]

Is that true in right-to-work states as well? I thought right-to-work was specifically to prevent involuntary unionization.

[rverghes]

Yes, but right-to-work is generally a reaction to involuntary unionization, as in it came after the involuntary unionization phase.