Because my passengers may not be comfortable with these habits, I do in fact abstain from any of these potentially distracting behaviors with passengers in my vehicle. In the plane of course, I have to do the things I need to but I also try to fly like a professional so that even though they are in a small Cessna, it feels like a smooth airline flight (well, as smooth as a light plane can be in weather). I want people to feel safe when I am driving and flying, so I try to use professional habits that put people at ease...
See, that's a good attitude!
I've been thinking about what you said about how busy it is in the cockpit compared to a car. I bet you'd shit a brick if the skies were as busy as a road though. Not every cessna has a proximity warning device but you know whats around you within about 1/2 - 1 mile radius. I'm not dumb enough to say that pilots dont need fast reflexes but generally speaking, crazy traffic conditions dont really happen once you get off the runway.
Once you're up, you have the time to actually read a map/look at little numbers on an altimeter/join the mile-high club/whatever. I think wierd shit happens more often on the road and you have to be more reactive then a pilot mid-flight. I'm not saying piloting is -easy-, just demanding in diff ways. If I was going to make analogy (and I -really- hate analogies) I would say its like dicking around on a phone while approaching a landing.
Could you imagine a blue angel pilot in the middle of an airshow?
"Yeah, I'm flying a 10 tonne machine 3 inches away from another 10 tonne machine at 500 mph... wait what? Why does my wife want me to pick up a gallon of milk from the..."
fiery crash ensues