Why do most drivers think they're better than average?

Because of a widespread bias called illusory superiority: people tend to overestimate their own qualities and abilities compared to others. Driving is the textbook case. In 1981, Svenson asked 161 students in Sweden and the United States to compare their driving to other people's: 93% of the U.S. sample and 69% of the Swedish sample put themselves in the top half for skill, and 88% and 77% did so for safety. Only half of any group can really be in the top half. The pattern has many names, including the Lake Wobegon effect, after the fictional town where all the children are above average.

Part of the explanation may be that everyone measures "good driving" by their own yardstick: if people interpret the question differently, a majority could each be above average by their own definition. Another explanation came from Kruger and Dunning, who found that in tasks like logic and grammar problems, all four performance groups rated themselves above average, with the bottom quarter showing the biggest gap. They argued that the people worst at a task are also worst at recognizing skill in it.

That second explanation is debated, though. Research by Burson, Larrick and Klayman suggests the effect is less clear-cut than it looks and may come down to noise and bias in how people estimate. And the bias isn't universal: much recent research has found the opposite, a worse-than-average effect, in many tasks, especially harder ones, and some studies indicate that East Asians tend to underestimate their own abilities.