There are several pieces that compare phone use bs drink driving, worth reading them all as they all test it differently but come out with similar results.
I'm working my way sloooowly through them (I'm meant to be working after all).
The first paper doesn't even pretend to compare, it samples many distractions and shows that distracted drivers have more rashes than drivers who are not distracted. It is salutary to read the table of driver distractions which have resulted in crashes. It does report that 18% of all fatal distracted-driving crashes, but this is in the context of "involved" meaning that police reported that the cell phone was either in use at the time of the crash
or was in the presence of the driver at the time of the crash. Thus the definition of a cell phone being "involved" is if it was
present.
To give a fuller flavour in a reasonably short quote:
"Most of the distracted-driving-related fatalities
(84%) were associated with the general classification of operating the vehicle in a careless or inattentive manner (could include cell phones [for States without cell phone identification on the reporting form],
eating, talking to passenger, looking outside, etc.). It should be noted that the distracted-driving-related crashes and fatalities may be associated with multiple
categories of distraction."
As I have said, allow yourself to be distracted in the wrong environment and you are a dangerous driver. Any distraction (including "looking outside" at the pretties).
Edit: It is a frequent occurrence that my passenger will ask as we drive along: "Did you see that ...[some very unusual / interesting sight]" and I'll reply "No, sorry, I was watching the road". sometimes though I have to allow myself to take attention from actually driving through high density traffic, at speed, with vulnerable road users weaving around me - so that I can replan my route or spot a landmark. The
safe way of doing this is to increase distance from other traffic and avoid sudden acceleration or steering (or braking so that the car behind doesn't hit me). This is I repeat the safe and correct response and not (as interpreted in at least one study) "impairment".