There are many different possibilities that revolve around this, but the most common one that I have been made aware of is the need to provide for the family or others.
If a family is poor, they could enlist an underage minor into working in gruesome settings just to make enough money to survive and obtain perishables to maintain function of vital organs.
The family could also use the child's earned money to obtain pharmaceuticals or other items that are not necessary, but curb addictions.
Finally, the child demonstrating that they are experiencing poverty may be a target for those employers and seek them out to enlist them.
when a family is impoverished, many of the children in the family work to help out with money issues. children will usually work illegally in odd jobs or in their community to provide some money for the bills and other expenses.
The fourteenth amendment says "All persons born or naturalized in the Unites States, and subject to the juisdiction thereof, are citizens of the United States"
