I work at a Teamsters shop. The International supports political causes and candidates with which I disagree. Enforced membership is a violation of my First Amendment rights. On the other hand, I very much benefit from the contract under which I work.
Search "Communication Workers v Beck."
I do not pay anything to IBT, as is my Constitutionally protected right. I gladly and gratefully send my check to the Local every month, less the 10-ish% that would go to Hoffa in violation of the Constitution, and enjoy all the benefits of collective bargaining I happily pay for.
As for "Right to Work," three words: Are, Ell, Ay.