It doesn’t matter whether the useful signal was deliberately placed or whether it is incidental: there is no necessary distinction. Why should it matter whether a flag was placed as a deliberate clue to wind direction (as is done at airports or on the masts of sailboats) or was there as an advertisement or symbol of pride in one’s country (as is done on public buildings). Once I interpret a flag’s motion to indicate wind direction, it does not matter why it was placed there.
