There were no under-16 sex workers at the metnieg (although if your figure is correct some of them may have begun working before that age); there were however sex workers or former sex workers whose first language had clearly not been English. No, I'm not saying that rapists can be judged by appearance or conversation, but some judgement of character and risk can be made, and probably more importantly, the woman can be seen by others with that man, the numberplate noted, etc. ie. saftey measures