Where has all the quicksand gone?

When I was growing up - not all that long ago - the adventure movies that I saw often featured something that is now becoming rather rare.  Quicksand.

How often have you seen (older) movies where the hero or heroin is running through the jungle and they suddenly find themselves stuck in quicksand.  Initially they are only up to their waists, but everyone knows that escape is impossible.  The more you struggle, the more futile it is and the deeper you sink.  Resistance is futile!

In many ways that scenario is an ideal way to build suspense.  Of course at the last minute the hapless victim was always rescued by someone who improvised an implausible solution to the problem.  Obviously the following advice was not known to them at the time:

Don't struggle. Since the human body is half as dense as quicksand, you won't sink much below your knees, or to your waist under rare circumstances. Fighting the suction-like pull can be exhausting and can cause you to sink deeper by making the solution more fluid. To extract yourself, stay calm and lean backwards to spread out your weight while backstroking to firmer ground. Kick your legs slowly to loosen the surrounding sand, and move deliberately toward the edge. 

That sounds easy doesn't it?  I feel that today's generation of teenagers are deprived of this phenomenon and this opportunity to learn.

Perhaps it is something to do with global warming?