No one does better doing two things at once. No one. No age group. No "I'm used to it 'cause I can text and watch TV all night long" teenager or an overloaded mom with a kid and a cell. Multi tasking while driving means you do multiple things less than 100%. It is true. It has been demonstrated a hundred ways from Sunday. It is fact.
The WSJ ran an editorial of sorts on the subject. It was with the same reasoning as 'guns don't kill people - people kill people" so don't blame the gun. Cell phones don't kill people ....people...well you get the reasoning or lack thereof. This type of non-reasoning can be used in a lot of situations I guess...seat belts don't save lives, people save lives ....trains don't kill people in cars, people kill people by hitting trains??? I dunno. Where does this silliness stop.