[jacobgkau]

My dad worked for the United States Postal Service for decades. He never joined the union, but he was still legally required to pay union dues, and the union was still legally required to represent him. So at least in some cases, yes, starting a union does affect all employees and practically requires them to "join" even if there's an option to not join on paper.

[inigyou]

Wouldn't it be better to join so that you can have a vote in the union operations, including to disband it?