I would suggest that, like so many of their media brethren (and sisteren) the reporters in this case took a fact and didn't bother to think "now I wonder why that is...?" and leapt straight to a sensational headline.
My kids attended a number of schools, and in most cases they were accepted in because the majority of the kids also had parents in the mob. It was understood that this "transient" population moved around, in fact I think when I went to enrol my kids at a new school the first question was "What was your previous posting".
The only problem they had was when I got out of the mob and moved to a small town. In this case the class of kids had been born at the same time, grew up together, been in the same class as each other every year and didn't like the concept of newcomers, especially newcomers who originally came from outside their county.