It’s a reference to the unnecessary apostrophe. The quote was something like “an apostrophe is used to create possessive nouns, it doesn’t mean ‘here comes an s!’”
I was in a market that had signs up not only prohibiting photos of the case of expensive booze, they also put one up saying not to take notes about it. Guess they're pretty worried about either corporate espionage or comparison shopping
Phones are sold that way, but I'm not sure if it's by law or convention. But there's no issue using either foreign-bought devices or apps that don't make a sound.
Either way I can't quite imagine the scene of someone confronting you taking pictures in a grocery store.