When I was a kid I had to join the American Federation of Musicians to play anywhere. Those old geezers despised us. All of the officers were left over from big band days and we rock'n'rollers were the only ones working. Our annual dues and our work dues were pretty much the foundation of the finances for the union.
Like most other unions it eventually collapsed and failed. Maybe it's a coincidence; musicians around here work for about the same amount today that we made in 1965. Plumbers don't.