Got a cite for that proposition? I bet adolescents who split have an idea that the authorities will be looking for them, to reunite them with family. Was Elizabeth Smart charged with not coming forward? She had to know somebody was looking for her.
Crime of what?
Bad manners?
Elizabeth Smart was a GIRL and she was being held against her will---
APPLES---ORANGES!!!
She already admitted it was a staged abduction so she had to have known police were looking for her which is obstruction. Running away under certain ages is a crime although little effort is put into finding them if the police know they are run aways. The police when they do find them just choose not to prosecute. Jennifer's problem is beyond running away which is not the crime in her case. Elizabeth was a true victim that was in a situation beyond her control.