Car crashes are the leading cause of death of children under age 18. The number of deaths has risen in the US even as it's fallen across the rest of the world. I have begun to wonder if phones are just a convenient scapegoat, even if the criticism is in the right direction.
I wonder if it's a combination of phones, car centric city design with wide stroads, and automatic transmissions. The latter two make driving very easy and boring, with long waiting periods at red lights, high speed between the lights, and you can keep your phone in one hand all along because there's no stick to shift. No wonder people are not looking at the road.
They absolutely reduce the number of variables requiring attention, except the problem and the source of danger is they only appear to. They make the way appear to be free of things to look out for, and so appear to require less attention. That's the "boring".
In reality of course, all the same kinds of unexpected events can still happen at any time. A baby can suddenly appear anywhere along one of those roads. But that doesn't mean the road does not encourage inattention.