I have lots of friends in the "movie making" business. Lots of crew members like camera department, set construction, etc. Before Obama care, the only way these folks could afford health insurance was to join the union. Even my actor friends have used the medical coverage as their sole reason. They are not looking to be SAG members for SAG work (we're in Texas so not necessary), but use it for the other benefits.
It's the only time it has made sense to me, within my lifetime. Otherwise, I think unions have way more power than what they need at this time. Now, they have to do things to justify their existence. Would things go back to the way they were before unions if they didn't exist?