The hard facts are literally in the last few paragraphs of this long article: "Tzi, the father [...] told Reuters he regrets that his children had gone to work

The hard facts are literally in the last few paragraphs of this long article: "Tzi, the father [...] told Reuters he regrets that his children had gone to work. The family needed any income it could get at the time, he added, but is now trying to move on." The father knew. "After the disappearance generated local news coverage, SMART dismissed a number of underage workers" Hyundai (SMART) knew. 12 year olds.