My experiences:

I've had two TSA locks disappear. I'm sure the suitcase was never opened as we had strapping on it that was still done up the way I did it. I filed a claim and had a check about 6 months later.

In the time before TSA locks I lost a total of one lock to baggage handling and there was other obvious damage at the time.



What I think happened in my case is that someone removed the locks intending to inspect the bag but then realized the strapping was going to make it take a lot longer than usual and they changed their mind--but didn't put the locks back.