That’s probably because they are treated better by our government than theirs.
It may also be that these kids are treated better in detention than at home.
Three hots & a cot, no beatings & no forced prostitution probably looks pretty good to some of these people.
Nicest place they’d ever been. If they ask about their folks, what do they hear — probably something like a court guardian will be looking into it. The children aren’t stupid, they knew there was a risk of running into law enforcement. Some might welcome that if they had an abusive life at home, or were dragged in here as nothing but pawns.