Talking on a mobile phone in a car, whether on hands-free or holding the phone to your ear, is a bad distraction. Either way you don't have enough attention on the road, and our road rule makers are starting to wake up to this fact. What will this mean in the future? Well, for one thing, we won't get any more car stereos with built-in Bluetooth for hands-free phone operation. There may also be some subtleties in the rules about using a dashboard-mounted phone as a navigation device (or dedicated nav devices, too). And if it's bad talking on the phone, surely it's bad to drive with misbehaving kids in the back too. How much distraction are we going to allow a driver to have, and how do we measure it? Perhaps it's time we got car manufacturers all working on robot chauffeurs built into our cars and left human drivers on the race track.
Mokalus of Borg
PS - I have a feeling it would change more things than we intend.
PPS - It would seriously cut into the taxi business, for one.