A month and a half into protests and I still can't believe comments like this are cropping up.
Selective policing takes place in many places. Often white kids/people aren't stopped at all, and if they are stopped any drugs they have are confiscated and they are sent on their way, or they are just sent on their way.
When doing stop and frisk in NY, a higher percentage of whites had illegal substances when frisked, but they weren't the ones being targeted. In some areas the percentage of black people stopped and frisk was above their percentage in that areas population, because it was being used as a means of harassment and back citizens were being stopped multiple times.
Not to mention legal representation. A white person with a lawyer is going to gain freedom far more often than a black person without one or with a public defender. White kids are also seen as needing guidance while black kids are seen as needing to be controlled and to have an example made out of them. This results in less dismissals, harsher judgements etc, just like with school discipline. Collective thinking is that black behavioral problems are an inherent character flaw, white behavioral problems are just a phase of which they will outgrow.
People don't consider even weapon wielding, wildly aggressive white folks to be a threat.
ACLU had a report they did a few years ago. The PDF is online. Google Selective Policing: Racially Disparate Enforcement of Low-Level Offenses in New Jersey.