SAG is also known as the
Screen Actors Guild or some approximation thereof. It has had a long history of clashes with the
studio bosses and while currently is working, the threat of another
strike is very close. When this happens, movie studios tend to
crank out the movies so that they have stock to coast on during the strike.
The main purpose SAG serves is defending the rights of the everyday actor. I've heard the rule for acting before: "95% of the money is made by 5% of the people". Most of the people in SAG have other jobs as well, and are scrapping by.