ToxicAdam said:
Well, criminalization of a child != that of an adult. The time they serve is less harsh than an adult would serve and often is much more effective. Their records are expunged at the age of 18, so they carry no baggage into their adult lives. Think of it as a government-aided intervention when all else fails.
I'm studying criminologyright now, so I'm not going to proclaim to be an expert, but the system you're describing has been making a move towards more and more just becoming kiddy jail, at least according to the material I've come across so far. The expunging of records is no longer automatic in all states (unless this has changed recently, Michigan hasn't had sealed juvenile records since 1988), many states have been implementing more and more means to charge juveniles as adults, juveniles can be convicted of the same crime twice (once in juvenile court, once in adult court), etc.
The juvenile justice programs that focus on rehabilitation/education do in fact help reduce recidivism, but the same is also true of many community-based, non-incarceration programs. (This also extends to adult prisons too, actually, but increasing overhead leads to cuts in the programs that seem to help rehabilitate).
Not claiming to be an expert, this is just undergraduate classes and all, but the 'get tough' movement appears to have dealt some serious blows to the supposed focus of the separate juvenile system.
More on topic, I wonder if prosecutors wouldn't 'need' the threat of jail (an argument I find specious to begin with) if they could demonstrate the ability to provide the services necessary for their protection/care. Beyond that, it's wildly inconsistent with the premise that children are not able to provide consent if the government holds them liable for engaging in sexual acts for money.