Public transports are really amazing with this respect. Many people are just absorbed by their phone not paying attention to anything around. Same happens in classrooms.
I have the chances to lecture to small groups of students. Phones are banned. I fully agree with what you said regarding focus, attention, etc. I witnessed the difference.
In short, we need to impose discipline to ourselves with our phones :)
Fully agree with banning phones in a classroom - people aren't there to use social media. My pet peeve is people crossing roads and not looking where they're going, and DRIVING and using phones! Oh, I won't even get started on that subject. I agree 100%, we need some discipline! :) Thanks for commenting!