If a private building wishes to jam cell phones, that's their choice. No idea why doing so would be illegal as long as they made certain on the door that cell phones are jammed inside. To not do so would be unethical.
Want to talk on a cell phone at a restaurant? Be my guest. People talk loud at restaurants to the people sitting around them anyway. No difference.
Personally I don't see why people would get pissed off by cell phones as long as they're not watching a movie or trying to listen to a lecture in school. Do I think that public schools should implement a policy of kicking out a student with a ringing phone at school? No, that's too much. If a private school wants to do so though, that's their choice. But sometimes students (even teachers) forget to silence/turn off their phones at school. One time my phone rang at school, and it was a wrong number. Thankfully the teachers just looked the other way, when technically they're supposed to confiscate it. Again today, a friend of mine had her phone ring in class. The teacher allowed her to turn it off without consequence. Most teachers are like that - they don't care if students have phones as long as they're not being used in class. The administrators, however, will GLADLY take your phone away.
What's very popular is students secretly text messaging. And you know what, that should be perfectly fine. If students don't want to pay attention, that's their choice. As long as they're not bothering anyone else.