Ridiculous indeed, but not in the way described.
Why would one have to say "up" or "down" in the first place? If the arrow would always be "up", there'd be no issue or problem.
Miraculously, us Europeans manage to get buildings built without any text related to stair direction. You see the arrow, you know it means "up". Easy, simple, unambiguous, error-free. We also know that stairs that go "up" also come "down".