How do you figure? In many union shops in non-right-to-work states you will be fired if you do not join the union within a month or so of employment. Do you mean that it is not mandatory in the sense that one doesn't have to choose to be in a union?
I am not going to be as hard as others for not understanding the byzantine union rules if you’ve never lived in a non-right to work state.
Any sane human being would conclude that you could pursue your occupation, regardless of this stuff. It’s just you would have to live there and breathe it in order to understand it.
It’s like the mob has a hold on your ability to earn the prevailing wage. Think of it that way and you’ll “get it.” And yes indeed, they WILL and DO come to your home at 8:30 at night, right in the middle of the Cavs game.