This is not about brakes. If the failure was caused by what it appears then this is about other negligence in having an adequet safety system. An Axle should not be sparking and grinding for miles and miles until it breaks. There are to many simple ways to prevent that from happening in this day and age. Cameras, sensors, and none of them really expensive.
Cameras did catch the sparks and axle fire well before the spill, but no one acted. I saw the film last night on Fox...