David, advanced drivers, if the requirement be that they should not have the radio on incase it distracts them, are by definition not normal, they sit outside of the norm.

I am willing to bet 99.9999% if cars on the road today have a radio in them and that 99.99999% of the people driving them use them. As 99.99999% of people on the road do not land up in an accident I feel that not having the radio on 'just in case' is abnormal.