America has a strange "Culture of Imprisonment". We're about 4% of the world's population, but have 25% of the world's prison inmates. Something that Joe Stalin or Pol Pot would be proud of.
We lock up young kids too. We even have a tradition of executing them sometimes.
Especially if they're Black.
Child prisoners are not uncommon. The above illustration is 'not' an exaggeration. I think we've all seen pictures of kids in orange in the news, and on TV. As I said just now thing is they're mostly Black or very poor White kids.
So who cares.