I read one of the first studies released and was amazed it took more than common sense to know phone use requires a high percentage of a brain's resources. This is why so many phone drivers out there are wandering all over the place. Anticipating their turn to speak. Avoiding uncomfortable dead time in communication. These are normally not concerns when talking to a passenger. "Hands free" won't change a thing, and now this has been proven as well.
Some people are better with it. Even heavy drinkers, or old people can be good drivers compared to BAD DRIVERS.
It's unfortunate that people don't have to prove driving ability every few years. It's unfortunate that everyone has to drive in America. Many should never be on the road but are (like my 94yrold neighbor)(or my aggressive wife).
But cell phones could be scrambled with a car out of park. If the gov't enforced a few standards onto auto makers. It should be handled with technology.