Back when cameras were cameras, and phones were phones, this was reasonably practical, and they did it, just like a sports venue might search for bottles of booze. Today, with everyone carrying a smartphone with a remarkably good camera and audio recorder, it's not practical to confiscate everyone's phone. "If the babysitter has a problem, he has to be able to reach me!!!"
It's not Apple or Samsung that will "control... how or when we use our devices." It's up to the venue to do that. There's a difference between enabling control, and doing the controlling. In a sense, the smartphone industry created a problem for all these venues, so they're providing a solution to those they negatively affected - undo some of the harm.
This seems a perfectly reasonable, though sneaky approach. Tickets to events contain nearly as much small print as a software EULA - the purchaser has "agreed" to a long list of things, including to not record the event. It might be nice, if this ever comes to fruition, that the device display a message: "Audio/video recording has been disabled by this venue, consistent with the terms of your admission ticket." GPS data could even identify the name of that venue.
I think some sort of notice needs to be mandatory, to indicate when recording is being illegitimately blocked. One might not be able to prevent a government from blocking recordings at a political demonstration, but it makes it hard for the culprits to hide.
