Not every sinkhole is indicative of poor construction. In many cases, the land underneath a building is simply unstable and no amount of reinforcement will be able to prevent a sinkhole from eventually appearing. So it is my belief that it is premature to blame engineering or architectural faults without further evidence.
The enormous Japanese sinkhole was repaired remarkably quickly which has naturally led to speculation that it was not filled in properly. These theories seemed to be confirmed when the sinkhole began to move again. However, in these early stages a small amount of movement is to be expected and does not represent a serious danger.
It could be bad construction, or it could be that the structure is just not meant to be at this juncture. When something keeps falling apart, that is usually a sign that it isn't supposed to be together The construction looks great to me. Japan should just let the think sink and stop trying to pick it back up.
Sinkholes are natural, especially in karst topography. They cannot be controlled and are the result of under ground erosion The only thing that can be done is to fill one in once they open and although one can question whether the Japanese Government did enough to ensure that the hole was stable before reopening the road, when the hole first appeared it government it is difficult to find fault for any government for the natural formation of sinkholes.