We're not just talking about unarmed people. Because unarmed people can pose a threat as well. If they try to attack the officer, reach for the gun, or hurt someone else, etc.
You seem to have a lot of faith in the media. I do not. I think it's extremely naive to count reporting frequency as proof of anything. I don't have the slightest doubt that the media picks and chooses events based on ratings potential--we've been told that by former members, in fact. That is, unless you believe only pretty "good girls" and cute little boys go missing.
A white, unarmed college student was shot multiple times and killed near where I live several years ago. I find it impossible to believe that this story would not have made the national media if the victim had been black.