And how's that working out for them? The median SAG/AFTRA member makes less than $1,000 per year from acting. And the pro sports players associations are tiny -- they exclude the much larger group of athletes who try to make a living playing sports but don't make the big leagues.
I dunno... I was a victim of this wage-fixing scheme, as were all of my coworkers at the time. And I don't know of a single one who would have preferred to have a union collectively negotiating wages.
The whole scheme was that the companies stopped their recruiters from cold-calling each others' employees. That kept wages down by reducing the opportunities for people to get a better salary by moving between companies (or threatening to). If wages were collectively negotiated, those opportunities would not exist in the first place.