At least in the UK it is illegal, same as talking on the phone while you are driving. Anything that distracts you from concentrating 100% on the road ahead will get you in deep water here.
Trouble is society is becoming faster and faster, people are expected to do many things as once, and to some they don't know when to stop or really just don't care of the possible implications to others. They believe they are great at everything, like the idiots who proclaim they driver better after a few drinks..
Unlike intelligence, stupidity has no limits