I think you've made an interesting observation. Certainly, within different cultures and different lifestyles, and certainly with new immigrants, it raises several new issues and challenges. However, I think if the line is drawn definitively that this is not legal, it will at least allow parents potentially a little bit of comfort, and hopefully children will start to make better decisions.
The truth is there are always going to be older people willing to exploit younger people, whether it's for the purpose of enticing them into a street gang to commit criminal activity or to perhaps perform sexual favours. I just think it will help society in general if the line is drawn in the sand: this is off-limits, and that is the law.