Some people can't look forward enough to recognize danger
On a similar note, quite a few years ago we had a gooseneck trailer in the shop with a Grove manlift sitting on it, the lift weighs 14KLBS. There was no truck attached to the trailer, it was backed into the shop and then the truck was pulled out. One of our fellas went to unload the manlift so he puts the ramps on (held by gravity) and up he gets into the basket which was positioned over the back end of the trailer and raises it up 5' or so. There were no stabilizers on the rear of the trailer.
Driving the lift off the trailer, the front set of wheels gets on the ramps and at that time the weight of the manlift tips the trailer down in the rear and in that process the ramps become unhooked allowing the front set of the manlift axles to hit the ground, 'bout 2' or so. The momentum continues to carry the lift rearward and the rear set of axles come off the trailer and to the ground.
Visualize this, a trebuchet. The operator was flung out and I can still remember this, went around 15' into the air and landed on his back, luckily for him not head first more or less flat onto a cement floor just missing a couple of steel benches, the corner of a steel work table and an ironworker.
Believe it or not ne never broke a bone, was off for 6 months and lost his sense of smell. To his credit he admitted he f'd up. He's retired now and when I see him I ask if he ever got his pilots license or got the blue cape to go with his outfit.