Not everybody drives the same way -- from how you describe it, to you driving is an all-encompassing activity, requiring presence, planning, attention etc. Don't get me wrong, that's ideal. Unfortunately most people don't drive like that. For many people, it's an incidental activity, a means to an end, done with the bare minimum of resources required to get by. That's why there are so many "accidents" and why you see so much stupidity on the roads.