I totally agree with what Kristian says.
IMHO, he describes the situation for what it really is. He's pointing out things a lot of people don't/or don't want to see. Mainly that, vulnerable or not, misguided or not, these girls fall in love with their "pimps" and they do as they please.
Also, vulnerable or not, misguided or not, they choose prostitution to make money just like any other escorts, courtisanes, SP, MP, etc. They are not chained to a bed with their legs spread so that clients waiting in line can go and fuck her.
The age thing is BS. We, men and women, can be vulnerable and/or misguided at any age and do things we shouldn't. Just look at the girls at the Ghomeshi trial.
We can do prevention. Family, friends, police and social services can be there for them. But we can't control people and we can't help someone that doesn't want help. As long as kidnapping, extorsion or violence is not involved.