They weren't that high frequency. I could hear computer monitors into my twenties at least. I'd guess somewhere around 20 - 22 kHz. CRTs were largely replaced by LCDs by my late 20s/early 30s, so I don't have a good sense of when I stopped being able to hear frequencies that high.
That only applies to TV sets, computer monitors operated at much higher frequencies outside the human hearing range.
They weren't that high frequency. I could hear computer monitors into my twenties at least. I'd guess somewhere around 20 - 22 kHz. CRTs were largely replaced by LCDs by my late 20s/early 30s, so I don't have a good sense of when I stopped being able to hear frequencies that high.
VGA monitors had a minimum horizontal frequency of 31 kHz (480p at 60Hz), way outside the human hearing range.