"Black Lives Matter" is a truism. Of course they do. It doesn't even need mentioning, so why did you mention it? "All Lives Matter" highlights an actual problem

"Black Lives Matter" is a truism. Of course they do. It doesn't even need mentioning, so why did you mention it? "All Lives Matter" highlights an actual problem of police incompetence and poor training that needs to be addressed, so why are you concentrating on "Black Lives Matter" and introduce racial context to the problem that affects the whole society?