As for the babysitter, deal with it. If you're not contactable for 90 minutes, you're not contactable for 90 minutes. This perma-connectivity is an entirely new phenomenon, and there's no absolute need for it. Essentially this argument is saying that the parent's inability to deal with lack of connectivity is a convenience which trumps the general theatre-going public's convenience of not having people talking on the phone, or who light up the people behind them because they're bored with the movie and are playing online.
Being uncontactable for a short period is not the horror that it's made out to be in these arguments. The good old argument that someone can't sit through a lecture without connectivity "in case Auntie Mabel dies", but of course it's just a cover for having phone access for other things. If one were to believe the excuses that get trotted out, you'd be forgiven for thinking that human mortality had skyrocketed since the public acceptance of mobile phones :)