It literally is a rare event. It may not seem that way when media everywhere you look (especially social media) repeats the same events over and over, but it literally is a rare event.

Is it completely unfathomable that the majority of shootings are justified?

You have unrealistic expectations. Not every situation can be de-escalated. And when violence is actively occurring, sometimes shooting someone IS the most reasonable de-escalation.

If you're saying most police forces around the world don't have guns, that's complete bullshit.

If you're saying most police forces around the world enforce their authority without pulling out their guns, the same applies to the US.

You are in an echo chamber and believe things that aren't true.