Unions can force non democrats to pay union dues and then spend the members dues on democrats.
Grrr
I am a "victim" of just that exact thing. I had to belong to the union for 8 years because of the job I had. Nothing galled me any more than for them to use my money to tell me to vote for people I would never vote for in a million years.
The day I took a different job that was not part of the bargaining unit was a very happy day for me.