In the early 1980s, transit officials in Washington couldn't figure out why traffic on the Beltway would grind to a near halt every day around the exact same time. The usual explanations didn't fit. Then it was discovered that a single driver was to blame. Every day on his drive to work, this commuter would plant himself in the left lane and set his cruise control to 55 mph, the posted speed limit, forcing those behind him to merge right, and you can imagine the effects. To his credit, this driver came forward in a letter to the editor of...