Think the difference is between "using your phone", meaning calling someone and audibly talking to someone, thus disrupting the movie for others, and "checking your phone", which is just looking at it, though inaudibly, though there might be some amount of light pollution depending on the screen brightness. First one has and will continue to be taboo, second one however, in my experience, used to be viewed with distaste, but is pretty common nowadays.

I’ve asked people sitting nearby to stop checking their phone as the glare can be very distracting. I might be immersed in the film but keep getting pulled out of the story by the distractingly bright light.

I also try to patronise cinemas that remind viewers at the start of the screening not to use their phone at all. I stopped going to the Cineworld near me because there was too much phone use (both calls and checking alerts) – and Cineworld had stopped the reminders at the start of the film for people to switch off their phone.

As someone who miraculously doesn’t feel this urge to constantly “check” his phone, I have to ask: what are you people “checking” for, exactly? It’s still there—it hasn’t gone anywhere. Is it the notifications? Why not just turn them off? I can assure you that there’s nothing on your phone that can’t wait an hour or so until the movie is done.

Out of 10,000 people “checking” their phones, probably around 1 of them is actually waiting for something urgent and important. The rest are doing it out of pure addiction.