Ergo, no one is forcing anyone to live and work in the United States, but if they want to then they have to pay taxes......just as no one is forcing anyone to work at a union company job, but if they want to then they have to pay dues.
From what I've observed, most people who gripe about unions have either never been in one and/or don't really understand how unions work or even how they benefit people, including the people doing the griping.
History has shown that unions and business work best when there is a balance of power between the two. When either side gains more power over the other then it hurts the ones who have less power. Right now business seems to be gaining more power over the unions and it doesn't look good for anyone who needs to work to earn a living whether they are union or not.