Exploring the UI is a perfectly valid method of discovering functionality. What’s the alternative? The phone interrupting you every 2 steps saying hey by the way, you can also do this and this from here?
Clicking on a kebab and getting a clearly-labeled “scan document” option seems like an eminently followable clue. It’s not like it’s a minuscule inscrutable icon three levels down.
Good UX provides clues to discovering additional functionality without intruding on the user.
What’s the alternative? That’s a question for a UX team - something Apple can certainly afford.