Make no mistake, for the convicted... go for it. I have no problems at all when it is a punishment for a convicted person. Someone else mentioned it being installed in a convicted persons car, and that car blocking all phone in it. I can probably agree with that, as I can not ride in their car, or I can make fun of them for my phone not working in their car when I am passenger. I am just vehemently against blanket punishment for the innocent.
Its funny you mention movie theater, as there I would be fine with it. Private party, I don't own the theater, compared to my car and my phone, and I could choose to frequent a theater that didn't do it if it bothered me vs government forcing it on me. I probably would go to that theater though if it was the closest, I don't care if my phone doesn't work while I am watching a movie. I do care when I am a passenger in a vehicle.