This has already been discussed to death on may other rv forums.
The truck in the original pic was WAY overloaded. That is why the frame failed. Camper was too heavy, it extended at least 4 feet beyond the end of the truck bed and there was an additional load way out past the end of the camper. Throw in the very bumpy roads found in many parts of Mexico where this happened, it was only a matter of time before it broke.
There is no "why they are failing" reason. Overloading by the owners is the cause.