In my state they have very strict laws about run aways too. Run aways can be classified as "at risk youth" and then they are under court jurisdiction.
They used to put the youth in jail when they ran away too, or missed school, or ..., but that just got struck down in our state supreme court because they were applying a criminal penalty to a civil situation.
It was kinda interesting to me, because they do the same (or say they do) for custody cases also. Reality is they never really did put people in jail though for contempt in custody cases, it would just be a tongue lashing and maybe some make up time (but only if it didn't interfere with the school schedule).