Speaking with a friend around me who worked in automotive, the unions are a double edged sword. They provide security for you, but they also provide security for a bunch of folks who realized they won't get fired if they put in the bare minimum. My friend found this incredibly frustrating.
Many unions here put large amounts of money toward political goals I don't support. If I want a job at such a company, under Michigan state law I can be compelled to pay the dues, even if the union is working against me politically. Until I can work somewhere without being forced to pay union dues, I am not interested in those jobs, even if they pay more.