To be clear: citing one episode in Seattle against the dozens and dozens of "less justified" killings isn't really making the case the "vast majority of police killings are justified".
FWIW: I'm in the region, follow these things, and don't remember that episode. I'd be curious to follow a link to that video if you have it.
Edit: I found it: https://www.youtube.com/watch?v=E8lebkOR_M4
You are deliberately misrepresenting that video! The shots are fired at 1:06, and the guy was, MAYBE in the process of stopping and turning toward the police. He was not facing them, at all. There is absolutely no "lunging" happening. His arms are tight to his sides, the knife isn't even visible, much less extended. And the shots are fired from WELL out of arms range, maybe 8-9 feet away. Hell, if you told me he was trying to surrender I'd half believe it. I'm looking at this and thinking... sorry, that killing was needless. He wasn't a threat. Or wasn't enough of a threat to make it worth killing him over.