In my country we had mandated unions for tech workers in various states. I paid the compulsory annual fee plus an additional fee that I didn't understand and can't properly explain what it was for.
Not once in 23 years in IT have they done anything for me. Not a single time. Every time we pushed for raises and someone contacted the union, nothing came back. When the company was not updating our salaries against inflation (that's a thing here), the union made a deal in our behalf so the increase would be bellow inflation. Multiple times.
I'd like to see unions working but they are a joke.
EDIT: Just remembered that we constantly had issues with overtime and they didn't care either.