What I've noticed about commuters is that they're on autopilot, and not watching. They've driven the same route every day, and ignore anything that isn't part of the normal traffic patterns.

Here's one I've noticed: A two-way stop just before a traffic light. Drivers will consistently blow through the stop sign if they see that they can make it through the green light further on. I'm super cautious about this situation, which occurs twice on my commute to work.