Seen this happen to some guys who were pitted next to me at the drag strip.
This happening does not interest me.
I have seen this happen too, but what is evident here is that the jack looks like it was on soft or uneven ground, the car moved, the jack fell over and bent the carry handle on it's way down, then the jack lever came up against something that was not moving - thereby causing the stress fracture to the side of the jack.
So what resulted was a car that was back on the ground and a broken jack.
An iron jack would have also laid down and dropped the car on the ground, but the jack lever and housing may have survived.
Bottom line is - I am not so sure it was the jack's fault as much as it was the person using it.
I've worked on teams that bought the original aluminum racing jacks from Brunn:
http://www.brunnhoelzl.com/warrior_jacks.html
And they were very nice, but the price was totally unaffordable by most of us GJ Junkies. Also, we had to rebuild them pretty much annually because they would leak down.