The go-to explanation, reasonably described as a knee-jerk reaction, to almost any instance of demographic “gaps” or disadvantage, at least by most of my colleagues in social psychology, and, I suspect, in many other academic fields, is ongoing discrimination by prejudiced individuals (prejudice is now often presumed to be unconscious, typically without evidence demonstrating such unconsciousness).
For example, in social psychology, the go-to explanation is “shooter bias” — enough studies show that, using realistic video games, laypeople more readily shoot unarmed blacks than unarmed whites.  Prejudice is also “our” explanation for the gender gap in STEM (despite ample evidence that other factors also play a role, and probably play a stronger role).
And I just discovered this in, of all places, the NYTimes Sunday Business section.
Evidence of killing-based-on-individual prejudice of officers would predict that police disproportionately kill blacks (per stop) than they kill other people (say, whites).
That does occur — but explains about 1/5 of the B/W difference in police killings; or, put differently, it fails to explain 4/5, most of which seems to occur because police stop a much higher proportion of blacks than whites.
“Well,” you might be thinking, “aren’t stops based on prejudice?”  Maybe a little. However, most stops are based on:
  1. Where police are stationed.  The country remains largely segregated, so if they are stationed in a racially homogeneous area, their personal prejudices are not going to explain who they stop.
  2. Descriptions of suspects in crimes.  Those descriptions come from the victims doing the reporting.  And victims report a proportion of black perpetrators that approximates the difference in b/w stops.
As usual, it is not that prejudice is irrelevant.  As usual, however, the left/social sciences obsession with prejudice and liberation narratives seems to have led to a typically tunnel-visioned approach to understanding this obviously important and  terrible social problem, one which, by attracting an insane amount of time/attention/effort/resources suffers from the massive opportunity cost of FAILING to understand larger and more important sources of police killing of blacks.
As usual, a diversity of perspectives, that would include non-leftist approaches that identify other sources of the “killing gap” besides prejudice are sorely needed to address this problem.