FUNKED..I think you have the right idea, but are perhaps misapplying it.
There is a standard of ethics which revolves around the concept of "other-directed harm". Meaning, as you stated, that society (not just government) has a right to intervene in an individuals behavior which puts other individuals at risk they did not accept.
The problem with your stance is that distracted driving actually IS "other-directed harm" as a result of the inherent danger involved...just the same way that drunk driving is.
We legislate behavior concerning alcohol, because it is not always a private risk...aggression, drunk driving, etc... are alcohol related aggravated risks that give society the right to intervene.
Talking on the phone AT HOME is not, so should not be subjected to the same intervention. Neither is talking on the phone on the sidewalk, or outside the restaurant (where it belongs, BTW), etc...
In the car, you become a danger to yourself and everyone around you, and prosecuting you after you've killed my wife and kids won't be good enough.
Much as we don't want to give up the right to chatter anytime, anyplace...we've gotta realize that there is a time and place for everything. The car ain't a good place of for most of 'em...