Many middle class white people feel “relieved” to see police. They nod at police as they ride through the street, or when they come onto the subway car. They feel safer. They certainly don’t feel threatened. And why should they?
At the same time poor people, alienated youth, black people, immigrants (especially the undocumented) become tense. The arrival of cops means the situation might suddenly explode in unpredictable directions. They feel under hostile scrutiny. They feel challenged. They sense that if they respond in kind they might be humiliated in public. In many cases their mothers warned them that a confrontation with the police can lead to death, and to get ready to swallow their pride and put on a passive, non-hostile poker face.
Many white people have no idea how many Black mothers train their sons to survive police encounters. There is role playing and repeated warnings. Mothers tell their sons when they hear of police murders, just so their sons understand that they can end up dead. “Remember to let them see your hands. If you are asked to go for ID, say “I’m reaching for my wallet” very loud. and try to make sure witnesses hear you too.”
So when a young black man is murdered by some psycho white cop, the assumptions are very different. Black people widely say “we know what happened here, it happens all the time.”
And many middle class white people “can’t imagine” that a cop would carry out a street execution and (in their own racist view) assume “he must have been doing something suspicious or threatening.”
And basically, the assumptions of Black people are perceptive. And the disbelief of white people are ignorant (and often willfully ignorant in a very racist way.) And the murderous hostility of cops (including black cops, btw) toward black youth is often very conscious, and very open when you get in close.