I do assume, though, that everyone who goes to see any show or movie anywhere is aware of the need to shut off their phones, not to say that everyone does (and yes, even the more sophisticated among us might well forget). It was just so unusual NOT to get the announcement which is what I thought made it "newsworthy", so to speak.
And certainly not to make a huge deal about this either, lol, but I do think it's always a worthy discussion. I agree with you that NOT hearing the announcement would be something to note.
But we really can't predict who knows the protocols and who doesn't. The most galling cellphone experience I've ever had was during an audition (I was the musical director). The woman was, I think, in the middle of her monologue, when a phone rang. It was HERS. She excused herself, pulled the phone out of her bag, and answered the call, right there, in front of us. Maybe an emergency situation she didn't forewarn us about? No - it sounded like maybe she was talking to one of her kids - politely saying that she was in the middle of an audition, and would call back later. Then, without any explanation, she started her monologue again.
By this time, I was practically underneath the upright piano (if one could do such a thing), flabbergasted.