Good luck to them with that. The only people it stops even today are people who don't mind being observed taking pictures. There are plenty of cameras that are easy to hide for anyone who cares to.

I can buy simple digital video recorders embedded in pens, watches, bluetooth earphones, baseball caps, ties, crucifixes and more from just a casual search of Amazon, for example, and that's hardly the state of the art in covert recording.

The more obnoxious anti-photographing policies people experience, the more attractive it will be to make recording devices less obtrusive.