That’s a specious argument because you can equally say “You can choose by switching industries or going to a non-union employer or starting your own company”. I

That’s a specious argument because you can equally say “You can choose by switching industries or going to a non-union employer or starting your own company”. In fact all of those can be easier than moving. Have you actually tried emigrating? Often not so easy unless you’re rich or have links to another country. In fact, it’s easier to join a non-union job than it is to move to a country without any form of taxation.