IMHO the comparison is to inform the decision point of whether to fly or drive somewhere, so the inputs should be limited accordingly: exclude drives that couldn't reasonably be flown.
Is it safer on average to do a long road trip, or fly? Historical crash data on long road trips (excluding commutes, local errands, etc.) probably doesn't exist, but if it did, that would be very preferable. Perhaps people crash more when driving unfamiliar roads, with additional fatigue of long durations, with additional distraction of kids, etc. Or perhaps routine drives are worse because one lets their guard down!
Is it safer on average to do a long road trip, or fly? Historical crash data on long road trips (excluding commutes, local errands, etc.) probably doesn't exist, but if it did, that would be very preferable. Perhaps people crash more when driving unfamiliar roads, with additional fatigue of long durations, with additional distraction of kids, etc. Or perhaps routine drives are worse because one lets their guard down!