I answered you. You just don't like the answer. The subject is watching your children in a store. I watched mine. Sorry that you have a problem with that.
For some, the subject is as stated above. For others, the subject is faulty workmanship- be it a mirror or a tunnel panel. I suppose it depends on your point of view.
For me, I feel a tremendous amount of sorrow for this family's loss and wish it had never happened. Is Walmart is to blame for having a mirror that was either installed poorly or is so poorly constructed that a 3 year old could knock it down, or is the parent to blame for not keeping a tighter reign on the child and for not anticipating the worse case scenario when out shopping?
This article is inconclusive and perhaps purposely so. I expect any video of the incident and inspection of the mirror hardware will provide better evidence as to what actually happened.