One kid was playing with a toy gun when the police just blasted him. Still, while it is mostly a record of dumb mistakes, that tells us very little about these people.

Really, people making dumb mistakes is not a very good metric for understanding who they were or what their overall situation was. It's a simplistic reduction of both evolutionary science and the world we actually live in.

Even if their deaths were cosmically justified, it remains perfectly possible to be sad about them. That's life. Emotional responses are independent of a victim's status under natural law or whatever it is you're suggesting.

You're free to laugh. That's well and good too, albeit probably not relatable for most people. Instead of acting superior, you should be grateful that those people think differently from you. If they didn't, you'd have nothing to laugh at but yourself.