I don’t think it’s *that* uncommon to hear high frequencies. I was always horribly annoyed by the high pitched whine of CRT screens when there wasn’t other noise to drown it out, and I knew other people who heard it well into adulthood too...but most people don’t so those noises usually get ignored, to our dismay.
...but yeah, most adults lose most or all of those high frequency ranges, so I’m not surprised most people don’t notice it.
They wouldn’t necessarily have to invent new bags. There are other people working on that, and while the temperature issues may make it harder to find a good alternative, there are alternatives out there they could buy instead of the bags they currently buy.
The plastic bag and whip waste are a couple of the main things that bother me about these too, so I’d like to see them try something different there too.