This actually happened to me on a flight into the US, with an expensive set of german kitchen knives in checked-in. In the US my suitcase was taken out of the normal line for extra checking (I guess because the knives showed up in an xray?).

They then later gave me my suitcase, but the entire knife set was missing. No documentation that it was taken. No one even cared. No recourse. And nothing came of it.

If I have something valuable that I couldn't take in my carryon again, I'd rather just DHL than trust the TSA to not steal it.