Speaking of the Musicians Union, I have a story:
In the early 70’s, Bill Graham used Monday nights to audition local (Bay Area) bands. The ones who passed were given slots on regular nights, opening for national acts. The Fillmore was a Union building, so to be able to perform there bands were required, if they didn’t already belong, to join the union. Most semi-pro bands, playing bars, clubs, weddings, corporate gigs, etc., never have to.
I knew some guys in a San Jose band who did the audition night at The Fillmore, joining the Union just to be able to do so. Induction fee, plus monthlies (whether you work that month or not). They played their set, and went home to hear back from the Graham organization. They instead heard from the Musicians Union, who fined them for playing below scale! Graham paid bands peanuts, auditioning bands actually willing to play for free to get on the Fillmore stage. Graham KNEW he was playing below scale, and that the bands would therefore get fined, and couldn’t care less. Ah, the life of an aspiring musician ;-) .
Speaking of pay.....for those who think being a professional musician in a big name band pays well: Denny Seiwell, the L.A. studio drummer McCartney plucked out of that environment for his early 70’s band Wings, gave an interview in which he disclosed that Paul was paying him $150 a week. He eventually quit, being unable to afford to work for Paul.