The thing with the phone over the radio, is you listen tothe radio, the phone you have to listena nd pay more attention to what is said and distracts you from driving. Dialing takes a lot of attention from diving. A 16 year old wishes she never got a cell phone in the fayetteville area. While using it, she went through an entersection, red light she did not see, and killed a woman driver in another car. I don't hear of too many accidents because people were listening to the radio, but I have heard a lot of accidents and deaths due to cell phone use.
The degree of distraction to a driver having a phone conversation, hands free or not, is greater than if the driver were actually to be having a conversation with passengers in his car.
It has something to do with the need to focus more closely on what is being said by the caller which requires the driver to shift more attention away from what he is seeing over to what he is hearing.
I think that is why the very often equate driving while phoning with driving under the influence. The same degree of impaired driving seems to occur the mroe intensely the driver has drunk or is having a conversation.
I remember people arguing that race car drivers today are wired-in while racing and their focus is not impaired. I think that the rebuttal is that,
1) Most of us are not race car drivers.
and,
2) They are talking about what they are doing and what the car is doing. They are not talking about yesterday's lunch, tonight's supper, what the boss said, etc., etc., etc.. So their focus is still on driving the car in the first place.
Does it make a difference, if you are the driver, whether you are on a hand held phone or a hands free phone if the conversation is about a list of items that you
have to pick up at the store on the way home? I think that it is an equal distraction either way.