I honestly think the ratchet was not properly engaged. As long as the ratchet is engaged and the full weight of that corner is on the stand the design of the stand means that you only have 40-50mm of a lever to lift in around 250kg.

I really think its a case of operator error in this story or else some sort of failure in the stand. I have tried a coule of times to shift the lever on my stands and I never have been able to with the car on the stand.

Its a very sad story and it should motivate people to be aware of the dangers when working under a car.