That’s not entirely true because there have been several cops convicted recently. The woman in Dallas who shot the kid from Harding comes to mind. Several other examples I can link if you would like. I agree that there have been instances which is bullshit but it’s not just a blanket “cops keep getting away with it”. Also remember sometimes cops get off because it is justified even if some don’t agree. Furgesson is a good example. The biggest problem normally is the media jumping the gun trying to be the first one out of the gate with the news that they don’t do there due diligence and they get people worked up without knowing the facts. (Not so much this instance but normally). A little off topic but you can not convince me that there would have been as many school shootings as there were if it wasn’t for the media sensationalizing it and playing it on the news non stop.
I've represented several police officers as an attorney. The qualified immunity doctrine makes it almost impossible to successfully prosecute claims against officers. Note the word "almost". There are always exceptions to the rule, usually due to bad lawyering.
And I couldn't agree more about the relationship between school shootings and how they are covered by the media. That's obviously far from the only important variable, but it definitely plays a large role. It's a tough situation though. Do you just not report them?