It's prison, there is no justification for functioning mobile phones. Guards have their radios, prisoners have a wall phone in the dedicated area they can get to when they're authorized to. Blanket the area with jamming, no reason not to. No rights are being infringed thanks to the presence of the wall phones.
As for theaters/cinemas, I'd agree but apparently there, there is a question of rights, namely the right to annoy everyone with a phone complaining about how much it costs to be there trumps the right to benefit from the play/film you paid the same bloody amount to see in peace.