Nothing wrong with warning other drivers, or pedestrians, or cyclists, by tooting at them if you can see they're about to move somewhere and potentially have an accident, or cause one.
Maybe cars should be fitted with two horns, one a polite little 'beep' noise, and one more resembling the blast from a cruise liner?!
And switching subject a bit, though still on 'noise', WHY aren't electric cars fitted with something that makes a regular engine noise? I recall seeing a blind person on TV a couple of years ago saying how dangerous silent cars are, for both her and her guide dog. Now I'm an occasional bike rider, I detest having EVs creep up behind me!