Is it just that they were white? I think there is that, but in this particular case it might be something just as despicable: the kids were local college students.

That makes them part of the community. Their parents could be upstanding taxpayers or worse, the cop's actual bosses. And even if their parents are from Texas, they *look* like local kids.

It's not despicable that the cops handle local problems gently. It's despicable that they don't treat all problems that way.