Class is definitely a part of it but it is unfortunately obscured by Race. If it were merely a class divide you would expect poor whites to align themselves with other groups that are disproportionately targeted by law enforcement but that doesn't happen.
In fact poor whites are treated quite poorly (no pun intended) by lawless law enforcement in their communities. Ever seen an episode of cops in a trailer park(greatly satirized by the show Reno 911:))? It is disgusting how the cops sometimes behave...even so, have you ever seen a rally of poor whites to protest poor law enforcement treatment?
There is an implied bargain that law enforcement exists to protect [whites] against "threats" from "others" and with that most whites avert their gaze when it comes to law enforcement abuse.
There is a lot more that could be written on this topic, HN is probably not the best forum for that:)
Remember, the people in power are white, but that does not mean that white people are the people in power.