When I'm motoring down the highway or walking/jogging near a street I almost never notice the people inside any of the passing vehicles. To me, cars and trucks are simply mobile road hazards, potential threats to be avoided—not framing devices around human beings. The exceptional times when I peer inside other autos tend to be on those rare occasions when I'm stuck waiting for a traffic light to change and get mildly curious about how many single-passenger cars are on the road, or how many drivers are illegally yakking on their cellphones as they cruise by.
So I'm often taken aback when a friend tells me that s/he saw me driving or running down a certain avenue. When I'm out on a pedestrian adventure and a car toots its horn in greeting, I have to made a deliberate effort to refocus and perceive the driver as a person who has recognized me.
For a long time I thought I was unique in this idiosyncracy ... until I asked a colleague (MLI, almost equal to me in some of her eccentricities!) who confessed that she too suffered from this special form of blindness. She told me of family and neighbors who note and comment whenever somebody is driving a vehicle outside of their customary stable—a new car, a rental or borrowed truck, etc.—and who clearly think of autos as analogous to a suit of clothes or a pair of shoes, rather than mere mechanisms of transport.
Another part of the perceptual spectrum to which I'm profoundly insensitive!