Actually you are wrong. You can be legally obligated to join a union in any non Right to Work state. Unions almost always have a union security clause forcing employers to only accept their members who are in good standing.

Unions are also not very democratic. They are democratic in principle but once again fall to the tyranny of the majority. If you are a minority in a union you are completely screwed unless you can trump their demands by using a protected class.

Unions have already served their purpose, well their original purpose was racism pure and simple, but their purpose of protecting workers is no longer necessary. Now they exist to only protect themselves.