Exactly who is “explaining to everyone else how unions work”?

The author. Didn’t you even bother to read your article? How about just your headline?

It’s claiming “Police Unions…keep abusive cops on the street”, when all they’re doing is requiring the hirers to adhere to the signed agreement. The author also talks about “secretive appeals geared to protect labor rights rather than public safety”, when a) agreements are usually confidential already, and b) Unions are defending the principle of adhering to the protocols in the contract, not the officer. If you noticed via the article, arbitrators (who are known to be fiercely independent and must be) side with the officers 70% of the time, suggesting the vast majority of appeals are valid.

Again, the Union isn’t saying don’t get rid of bad cops. It’s saying if you want to get rid of them, follow the steps you’ve laid out in the agreed-upon contract.