By improving the experience for the surrounding diners. Busy restaurants are noisy enough from the quiet conversations being had between the diners themselves. Ringtones, or even the reverberations of a wireless phone's buzzer on a wooden table, only add to the noise level.
I'm far more distracted/upset by large groups of people laughing or yelling - teens/adults/whatever - than I am by someone talking on their phone. Even multiple people on their phone is much quieter than a group of coworkers from an office out to let off some steam before the weekend. But... large groups of people tend to order more and have 20% gratuities tacked on, so I doubt they'll be asked to leave.
I'm far more distracted/upset by large groups of people laughing or yelling - teens/adults/whatever - than I am by someone talking on their phone.
People really have a highly selective ability to be annoyed by things that they are judgmental about/think that they are better than -- or even worse that they think make people better than them -- especially if it triggers their jealousy/resentment. If someone is getting texts or calls, that's incredibly annoying to someone who gets no texts or calls for obvious reasons.
Some years back we took our young children out with their grandparents to a family restaurant. It was mid evening on a Saturday night and the place was full and very loud, with escalating conversations, people having fun, etc.
My infant daughter dropped her fork. I happened to catch a woman nearby -- likely barren and fervently vengeful -- giving the most hateful, glaring look I've ever seen, and I would imagine she went forth to declare how her night was ruined by our much quieter than average table. I recall this experience whenever I hear some railing about children on airplanes, etc -- I imagine that much of it is selective, desperate clutching for offense, and it's much the same regarding people and their anti-smartphone spiels.
