Actually, as ushers we had to ask people not to take pictures - this was a rather thankless task - it varied from concert to concert and promoter to promoter. But Bernie Fiedler, the promoter of the Lightfoot concerts back then was not deeply loved by the ushers. Before the doors opened he would lay down the law about cameras, flash cameras in particular, and smoking that we were expected to mention and enforce.
However,surprise, surprise, just before the lights went down, he, with cigarette in hand, would lead a group of the Beautiful People out from a stage door, fresh from backstage, to their front row centre seats and guess what they would inevitably be carrying cameras and smoking cigarettes. This made the ushers look particularly stupid as most of the audience didn't know who this guy was and they wondered why we weren't rushing up and telling that particular group to stash their cameras and put out their cigarettes.
A bit of usher trivia, one the ushers then taking to people to their seats on the first or second balcony, usually, was
Tom Melissis Dewey of Due South fame.