There's no oligopoly of tech companies like hollywood studios though. Even the salary-collusion BS was a very small group of companies and illegal without union protection.

Also the Rock may pay his union dues because (a) he's required to be a memeber and (b) the cost is immaterial to him. The top performers are usually hampered by unions they'd be fine without; he's not going to need the pension and health insurance the collective bargaining agreement gets him.