This is overly optimistic. If this were true, most people driving an automatic transmission would be safer drivers in light of the lighter cognitive load. But that's not what happens. Instead the brain is overwhelmed by autonomous friending and vending apps until the car becomes an autonomous ending machine.

My n=1 experiment with driving a manual for 40 years in urban environments coast to coast is that I can't focus well without it and my experience doing half of that data set on a motorcycle just enforces that conclusion.