"You have nothing to suggest that other groups are doing this,"

In point of fact other groups are doing this, all over Europe. British authorities are seeking advice from the Dutch who have been experiencing a near identical new-wave of pimping - specifically targeting, grooming and internally trafficking young schoolgirls - for at least a decade (they call them "loverboys" over there, and there is a UK based campaign of the same name.) So no, it's not a specifically Pakistani based phenomenon by a long straw. If you are genuinely interested in the subject, then I'm sure you will be able to find plenty of articles about it.