Basically the reason why Vietnam won because the Vietnamese wanted to win more than the Americans did. There were a couple of reasons for this. First, the Americans were an invading force, and the Vietnamese were fighting on their own soil. Second, the Americans were not willing to make an all-out commitment to win.
Answer: The reason for child labor laws
Explanation: What these two are attempting is extremely dangerous. If the machine was activated, they could easily been drawn into the mechanism and injured, if not killed.
The company probably saved a few pennies by employing the children, but could have put them at an increased risk for injury. The scene depicted here was far from unusual for the times as companies would do anything to save money. Without regulations, these practices were commonplace in that day and age.