So many of these stories are months or even years after the fact because unless the media gets on it, the incident gets buried immediately, and by the time the media gets ahold of it any investigation is challenging because it’s either so long after the fact or police “lost” evidence.
It being reported immediately starts the accountability and makes it much more likely that there will be an investigation in the first place. Either you are too young to remember or just weren’t noticing, but reports of police killing unarmed minorities was exceptionally rare a few decades ago. Cops got away with anything and everything. That’s where Black Lives Matter came from, getting the mainstream media (and the justice department) to care when a black person gets killed.