Pretty much no phone is directed at everyone else’s face all the time, that alone is the huge difference. It’s the differences between someone using their phone and someone actively holding it upright to record the crowd. Surveillance cameras might be out there too but they aren’t sighted by everyone (different by country, some even have to deleted after 24h, unless there was a crime).

People quickly would tell you to stop recoding, if you’d hold up your phone all the time, even in situations where you’re closer to each other, like in public transport.