You raise an excellent point. If businesses can run jammers without fear of prosecution, they will almost certainly post a sign that says "cell phones jammed during show times" or some such. That way you actually realize it's happening. Under the current system, more and more people carry personal jammers, and you never know when you'll suddenly find yourself in a dead spot.
Yes they sure are...;) Another useful gizmo is the super small universal remote that hangs on a keychain. It has only one function.....off.....in 45 different TV codes.
This kind of situation is why the Founding Fathers regulated interstate commerce to the government.
It does not solve the problem at hand: the problem of rude patrons. Rowdy brats, loud commentary, and so forth will still be problems. Last time I went to the movies, my experience was ruined by someone who aimed a laser pointer at the screens for 30 minutes. No one did a thing about it. You want someone to blame--blame the eunuch management.