“This is a difficult recommendation, but it’s the right recommendation and it’s time” -Deborah Hersman, NTSB Chairwoman
There is just shy of NOTHING as important as driving when you are driving. To make a call that just can’t wait, pull over. To receive a call that just can’t wait, use the hands-free and tell them to wait, then pull over. If it can’t wait and you can’t pull over, that’s an emergency and there is an exception for that in the recommendation.
Note: what you are getting from the grocery is not an emergency. Facebook is not an emergency. You suck that it has to come down to the law to get you off the phone while you are driving.