I don't know why you added "Try again", especially because I intentionally specified "Individual contributors". Your response also highlights what I was talking about: unions do not hold back their highest paid members while bringing up the bottom for their lowest paid members, just as is the case for SAG.
Most unions cap pay, e.g., [1]. A simple Google gives plenty of evidence.
Your claim about SAG is also wrong; SAG has plenty of pay caps too. For example, here [2] is one explained on their own site. They've always had them and likely always will. There's plenty more.
Unions extract higher pay by making a monopoly on labor (and US antitrust law had to carve out a special monopoly exception for them). This monopoly obtains higher wages for those in the union at the cost of those prevented from working by the union and by increased prices to the surrounding economy. These are all standard econ results.
