The only counter example to this story I’ve heard involved San Francisco International.

The TSA / luggage handlers were repeatedly stealing things from checked luggage. Of course, nothing was done to follow up on the police reports that were filed.

Then, one day, airport security stole a checked service revolver from a retired cop. Once that was reported, the police immediately ran a sting operation, and arrested the perpetrators.

Not sure what the moral of the story is.