"
Is this a fact? A 30' fall usually kills? That's around 3 stories, I guess. It seems that people have survived that jumping out the window in fires."

Don't know of that is true or not.
But if it is - I am one of the lucky few.
I took a 25-30 foot leader fall while rock climbing many years ago. Came away with a bloody nose and a broken ankle. Could have been much worse.

There are infamous stories of people who took longer falls - and died. But death was not immediate. One guy got up after a 60-foot fall, and was talking to people for half an hour. But eventually died due to rupture of his spleen and internal blood loss.

As far as the original story is concerned .... the desert is tricky at night because the lighting can be very sharp. If there is a full moon (or mostly full), bright areas are quite bright and shadows can seem very dark. The visual cues may have deceived these guys into believing they were on less dangerous terrain than they actually were.

Pete 2