Distorted accident figures came from ATSB some time ago, and I believe that's where the "motorbike" comparison came from.
In the days when we used to get proper figures, the accident rate of the "private and business" sector was consistently the same as the agricultural sector. In other words the private or business pilots had virtually the same accident rate as the "cropdusters"
Charter flying was considerably safer .
But ATSB saw fit to lump the two groups together and produce a misleading figure, along with the "motorbike anomoly. WHY?