Many Belgian car wrecks result in crumpled left sides because many Belgian drivers fail to yield to cars that have priority from the right at road intersections.

There is nothing wrong with the right priority rule in itself. But this rule is waived if the right driver hesitates before entering the intersection. Since this waiver requires a judgment call, it is not surprising that "misunderstanding" leads to many accidents when left drivers fail to yield. These accidents are particularly serious and frequent when a minor road intersects with a major one with fast moving traffic. The absence of stop signs at intersections adds to the confusion.

As a result, Belgium has 22.4 traffic deaths per 100,000 cars compared with 18.1 in the U.S.

Traffic signals and rules are prime example of coordination rules in coordination games. Some rules might be better than others. But inconsistent or unclear rules are a recipe for disaster. Inconsistent or unclear rules might even promote aggressive driving behavior by turning a co-ordination game into a game of chicken.

Most of these rules do not emerge spontaneously and must be codified and enforced by some central organization. They are more reliable if they are hard-coded into hardware such as traffic lights and stop signs.