Just for the sake of contribution, I felt emotionally charged when I read about the 16 year old.
Even if you're 13, if you do something heinous enough I believe you should be tried as an adult.
Rape is not something children do. They learn it from an adult, which means that teen watched rapes whether they were real or fake and said "hey I know this causes pain and suffering but it makes my dick hard so IM GONNA DO IT ANYWAY. Then he streamed it because he wanted people to see the pain he was causing.
You don't do that shit by accident or because you're misguided. You do that Shit because you're a sociopath who gets off on the pain of others.
I don't care how old you are. If you rape, you know what you're doing and you deserve whatever fate awaits you. Personally I hope he gets hung by his dick until it severes, then maybe have his eyes scooped from their sockets with a grapefruit spoon and livestream it. That won't happen though so I hope someone shoots him in the face so he has a closed casket.
As for minors, I think if they do adult stuff they should be tried as adults with very, very careful and scutinous judgement. For example, if a 14 year old steals a car, they shouldn't be tried as an adult. Big stupid mistakes happen.
Now if that same 14 year old stole the car, drove to the store, then robbed the place with a weapon/ran over a person I would say try them as an adult because they clearly know what they were doing, they just didn't comprehend what it would do to others.
As for minors in prison, if you fuck up hard enough to go to an adult prison I can't sympathize with that.
^ just opinions, up for discussion/debate