You're not wrong. The issue is, it's hard to make a good API for this; anything else is basically dealing with global state, and so you don't have a guarantee that something else doesn't re-set it to something else while unwinding is happening, etc. I do have one more thing to say on this, but it fits better in a reply elsewhere in the thread :)

panic! does return a non-zero exit code, but isn't really designed for good end-user output.