If they can only hear it way above the threshold of physical damage, that's a good anecdote but it's definitely not relevant to music playback.

Sensitivity to audio falls off a cliff as you approach 20KHz.

And that assumes you have young ears. If you're older, chances are it's nowhere near 20kHz.

At normal listening levels, yup. I'm 30 and I can certainly hear the hideous 19 kHz anti-rat blasters they have all over shops in Tokyo (and I think they almost certainly cause ear damage and should be illegal - IIRC they are marketed as putting out 138dB SPL!) but I am rather unlikely to hear the difference between music low-passed at 19kHz and 20kHz.

> I am rather unlikely to hear the difference

Especially if your hearing has been damaged by repeat exposure to 19 kHz at 138dB SPL.

I do try to run away or cover my ears when I run into them...

> from all accounts

From all accounts? Don't you mean from one account?