Well, when I was 12, I pushed trollies over weekends outside Spar to make some pocket money. I did this for about a year till Spar actually offered me a job as a packer. I loved it. I loved working there, and it taught me how to work with my money from a young age.
Till some douchbag customer got butthurt that spar employed a 13 year old and reported them. I got laid off, and went back to pushing trollies. I was heart broken and couldn't understand why I had to wait till 16 to work, when I was fully capable and enjoyed it.
My point is, perhaps these under aged children enjoy working there. I mean it's an income even though it's cheap labor. I'm pretty sure Foxconn isn't holding a gun to their heads and forcing labor on them... Just my 2c.