There are many ways to drive with reduced attention (BTW, that's n adverse side effect of the modern very helpful cars), phoning while driving is just one. One German driver recently was found being online with her laptop on her lap.

Why do you only talk about cars and mobiles? Is it not forbidden on bicycles as well in your countries? I'm living in a bicycle town and I get mad at the phoning bicycle riders changing direction without indicating it. I then overtake them and ask very politely if the next time they could bother to indicate a change of direction with the hand.

The looks I get then or the words I hear indicate that this is a totally silly damand. It's only more fun to ask the same question of a cyclist with an open umbrella during heavy rain.

Wolfgang