I wonder if said unions decided to give people a chance to support if they wanted. I'd be very happy with unions if they did that, in fact, I could even maybe support unions as a 'good' influence instead of a 'bad' one if they'd agree to voluntary participation of their members.
That's not the way a Union works. Despite the English spelling, there is no "I" in Union. There is a "We". Take that away and suddenly the whole Union no longer works.
Imagine a workplace where 8 people supposedly have the same job. 4 of them are members of a Union, and have rules about what they can/can't do. The other 4 are not bound by those rules. How efficiently do you think that dep as recent is going to work? Not very well, as I see it.