I suspect one reason that there is no agreement on whether caning on the hands is more painful than on the backside, may be purely physiological. As I understand it the distribution of pain receptors/transmitters (nociceptors) follows a bell curve in general terms, but in all cases, there is a quite high minimum number on the hands…
That explanation sounds too complicated to me. Apart from the obvious differences in the size and weight of the cane and the force of the strokes, there are a large number of factors that influence how much a caning hurts. Some are seemingly trivial such as the temperature of the room or the time of day.