I don’t think they’ve ever lost a donkey or a tourist off a donkey. Never. An old high class Bostonian lady once asked a mule-skinner if there was a dining car on the mule train to the bottom, however.
In law school, I heard of a case in which a mule acted up and pitched its middle aged woman rider off and over the edge into the abyss. The legal issue was how to get a key piece of evidence in: that one of the muleskinners remarked spontaneously that the mule at fault had been troublesome ever since it had been demoted from lead mule to a less appealing position in the middle of the mule train.
They use mules and have not lost one with a rider. They have lost pack mules though; successful pack mules generally become the riding mules.d