It's completely sensible for most people to believe they are above average drivers, and all be correct. This is because there isn't a single objective measurement for "good at driving."
Imagine that 50% of people are cautious drivers, and 50% are fast drivers. The cautious drivers think being cautious is more important than being fast, so they all believe they are above average. The fast drivers, vice versa. Everyone thinks they're above average, and they are by their own standards, no delusion required.
Imagine that 50% of people are cautious drivers, and 50% are fast drivers. The cautious drivers think being cautious is more important than being fast, so they all believe they are above average. The fast drivers, vice versa. Everyone thinks they're above average, and they are by their own standards, no delusion required.