This is very likely the closest to the actual truth that we'll ever get.
It takes both time and effort (read $$$) to properly compact dirt that's been disturbed.
No doubt it was tested, but these tests can be rushed, altered and even outright bought.
This problem is just another example of the consequences of rushed construction, and to an even greater degree, a contractor who is more interested in profit than quality.
Sound familiar, TDC???
Thank you, and you are correct.
Let's say they did their testing (the proper way for sake of argument) - even so, time is the real test here. The bottom line is stuff like this happens, not to mention the abuse Disneyland's surfaces get anyway. There are so many factors that play into this kind of thing, I'm not surprised that it's being assessed.
So far they've replaced the floor in Flo's Cafe, and Mater's Junkyard Jamboree. I'm not sure what they most recently did to the Cozy Cones, but it doesn't come as a big surprise to me that they're going to have to replace the entire roadway through Radiator Springs. Seems to be a trend.