You probably have that perception because cases that you dislike stand out like sore thumbs, while all the other title edits escape notice. If you think about it, that pretty well guarantees the feeling "it seems to be applied with little regards for its usefulness"—because all the "useful" edits are by definition excluded.
You can use petercooper's title edit tracker to see some of them: https://hackernewstitles.netlify.app/. It doesn't show all of them, and it doesn't distinguish between edits by submitters and edits by mods. Probably we should just publish the official list—I feel like title editing is the most consistent and easily defensible thing we do.