And therein lies the heart of the problem......
for these (mainly) Pakistani muslim men, under Sharia Law, which is the only one they actually respect, these white, non-muslim, free living girls are there to be taken as sex slaves and used in any manner they think fit because they are regarded as the lowest of the low - and there are many videos out there with them saying as much. So, for them, it IS legal to do this.
Until their minds can be changed on that belief (probably never), or until the punishment is sufficient to make such behaviour not worth while this problem will not go away.