The study might just indicate poor enforcement or that hands free cell phones aren't any better. NJ has a handheld cell phone ban but I see cops themselves driving along with a cell phone pasted to their ear. Cell phone driving is as much a hazard now as drunk driving used to be. Many drivers could really use robotic driver assist as they are no longer really driving but just responding. Safe driving requires actively predicting the future a few seconds out, and that can't be done in the middle of a conversation.
AAA did a five year study that said only 6% of accidents were caused by cell phone use.
Is using a cell phone a distraction, sure.
Is using a cell phone more of a distraction than eating, drinking a soda, listening to the radio, a crying baby strapped in a car seat, kids fighting in the back seat, talking to your passenger - I don’t think so.
The issues is distracted driving.