Probably more important in an ATC context than a flight deck setting. Tail numbers come to mind, as you said. Although I could see Part 91 operators mixing up airport identifiers with O and 0, airlines don't fly to airports where that matters... intersections and navaids are all alpha... approach names aren't going to have any ambiguity... so I guess one could argue it's ok? Still, you're right, it was a weird choice not to disambiguate them.

(Also, I'm super jealous you went to the ATC academy. By the time I seriously considered it, I'd aged out.)