I was at a CAKE concert at Brewery Ommegang last summer. Not only did John McCrea tell the audience not to record, but he actually specifically called out the two people who were willing to defy him at some point during the concert, embarrassing them into putting their cameras away. It was great! Having a hundred huge smartphones and iPads with the brightness turned up too high interfere with my view the whole night is a real annoyance. I went to a How to Destroy Angels show last night. I had a balcony seat, so I didn't have to worry about idiots obstructing my view, but I did have to put up with idiots taking flash photographs. HtDA uses very complex lighting sequences (it's really amazing), but whenever there was a dramatic darkness upon the stage, it was invariably interrupted by some imbecile who left their crap camera's flash on auto.