something else occurs to me: the distraction of someone talking during a movie is well known and understood. But people shining lights during a film is a different category of distraction. It has little to do with someone communicating outside the room, more with my eyes being pulled away from the screen, reminding me I'm in a movie theater after all. (this whole thing with serving food while watching a film seems pretty weird anyway.)

Peer pressure is really the only way to get people to change their habits in public spaces, if it's just the manegement that doesn't like it, not that many people are going to care.