I don’t know how many times where I’ve been in a weaving situation because a cell phone driver was doing 10 or so under the limit; sometimes in the FAST lane. I once saw a man so engrossed that he was doing 40 in a 70. Evidently, the first brain function to go is cognizance of the speedometer.
There is a car I see every morning that I go into the office, the person drives 10-15 mph under the speed limit, if on the two lane(in each direction) part in the left lane and in one of the middle two lanes on the five lane section has their hands at the 10 and 2 positions and is obviously NOT talking on the phone.