Unionized actors and actresses could push for equalization of pay for all in the profession. It's perfectly consistent with the socialist world view that people like Sean Penn seem to espouse. Sean, it would make your friend Hugo Chavez very proud of you if you pushed for equalization of pay among all actors - as part of a union contract.
Yes, it's sarcasm, but the concept is very consistent with what they are asking of others in society. Without hypocrites the ranks of the left would be thin.
There are already many unions for actors/actresses (Screen Actors Guild for one) and the people who work on movies such as cameramen and engineers. I know there are writers unions too but am not sure about journalists.
Your argument shouldn’t be about the income disparity within the entertainment industry, it should be between the entertainment industry and everyone else.