I once belonged to a union. An employee had no say in the matter, you were just a dues paying worker.
I was not informed that I would belong to a union and have to pay dues! I think that had I been informed that I would have to belong to the union and to pay dues I would have been fine. I first found out when I got my first paycheck. I asked my manager at the time what a particular deduction was for. I was told that it was my union dues and it would come out of every paycheck I would get!
I did not feel too bad then, but when I informed the manager I did not want to belong to the union, he told me that I had no choice, that I would have to be in the union and they would be taking my dues no matter what I said.
I thought that you could opt out of the union at any time. I was sadly mistaken. The union never did anything for me except make me a lot more poor!!