There's inherent difficulties with trying to compare ground transport statistics with aviation statistics. Do you choose distance travelled, or duration in the vehicle? How do you get the granularity you need when many types of things are lumped together eg agricultural flying is usually included in GA yet is a high risk activity. Similarly for other aspects of GA eg private vs aerial work or public transport ops and also the ratings & experience level of the pilot.
Similarly for ground transport. There are many, many fender benders that go unreported. Again, how much differentiation is contained within the figures for driver age or experience or time of year/day or type of vehicle or was it employment or personal travel related etc. Probably more than in aviation but I'm not sure.
The work vs personal travel distinction is a good one because personal travel is something with a reasonable equivalent in aviation ie private flights.