As to your second point. Attitude and culture really are the key here. Sadly, mobile phones are at a point where they are almost issued at birth and critical to our daily lives. They have saturated everything we do. I'd happily stick my phone away for a day and enjoy the peace and quiet from the kids but the younger Drivers have a different attitude. They will stick it in airplane mode and not turn it off because they see that as 'off' I've seen Drivers exit a cab and within seconds have their phones to their ear or are already checking messages. The 'Railway' just cannot keep up with the modern generation fast enough.
They are also very much tripping over themselves too. We cant use them, they are evil things that lose your job and can stick you in the clink. However, lets issue one to everyone and tell you to use it when required. Our GSMR has a direct link to Fleet but they still encourage you to use your mobile. Even the rulebook allows for mobile phone use where needed. 18 odd years ago it was black and white. DO NOT USE THEM. Now its a bit grey which some use regulated.
The other giant pink mammoth sitting in the corner of the room is more obvious to Internals. It isn't the phone that's the problem. It was the distraction. It doesn't matter if its a mobile, tablet, DAS, or GSMR or even quickly grabbing your bag. Doing something at a safety critical time can, and does, lead to incident.
There is a greater issue with situational awareness and the need to be focussed at safety critical times.