There's no inherent contradiction with a majority of drivers rating themselves above average: each driver is free to prioritize "good driver"-traits differently

There's no inherent contradiction with a majority of drivers rating themselves above average: each driver is free to prioritize "good driver"-traits differently; e.g. if I value road safety and my neighbour values total travel time, we are probably both objectively better drivers according to our own metrics. That said, 93% of car drivers are worse than me. Obviously.