It also needs a public safety system that just stops killing so many people!
Trying to figure out how much of that 3x is because of legitimate differences in danger to the police, how much of that legitimate difference in danger is provoked by different police attitudes towards white and black people, how much of that attitude could be changed by training, etc. etc., is a complex maze of "but what about..."s that raises doubts about whether we'll ever get to a solution, even if we get to do a lot of blaming on the way to not solving the problem.
Starting the other way--"forget how many more, how do we just get police to NOT KILL PEOPLE" saves everyone. Heck, the disparity could even get worse from 3x to 4x let's say, but if you reduce killings by police by 3x at the same time, you've saved 56% of the black people who would otherwise have been killed.
(Not saying that we shouldn't care about the disparity too--just that the "OMG why do police kill so many people" angle seems by far the easier way to save black lives (and non-black lives). Also, I think that if the total deaths went way down, the disparity would very likely drop, since a lot of the flimsy excuses wouldn't work any more.)
In my most cynical moods, I wonder whether the only reason why the far right who is supposedly so distrusting of government-condoned violence is so accepting of the ridiculous number of killings of white people by police is that they feel it's worth it because the police kill black people so much more often.
I don't think I actually believe that--people tend to be more complex than that, and consciously condoning the occasional unnecessary killing of your friends is a leap almost nobody is willing to make. It's more likely a moralistic good vs evil frame of mind, where the police are the good guys and the ones who die are bad guys who deserved it.
But the amount of death total that society tolerates is quite shocking. (Then again, if you look beyond police violence, our tolerance of murder and other violence is even more shocking, so...at least we're consistent in a deeply depressing sort of way.)