What's the problem with warping brake discs these days ?

Cossies suffered (still do) from them, evo's suffer too apparently, and, reading stu's post on his M5 purchase, it would appear even top of the range BMW cars suffer from this problem.
I am sure many other cars suffer from this too.

What I don't understand is that in 20 years, nobody's come up with a solution yet !!! Is it a steering geometry / stability problem ? The roads ? Too small a disc setup for the weight of the car ?