Is detection of EM radiation really that easy? Broad parts of the EM spectrum are heavily attenuated by water - this is what makes underwater comms difficult.
That may be true, but the OP is talking about risk, so you need to compare those figures to the population breakdown. The risk experienced by a white person (representing 45% of those shot by police and 72% of the population) is significantly lower than that of a black person (22% of those shot by police, 12% of the population). Similar story for other minorities.