When MP3s came out it was marketed as better than CD quality.
very few know apart from audiophiles and us, LOL, we know different. Another one for the null testing courtesy of George Massenberg.
But most punters are content with MP3, not just for file size. Nothing is being broadly promoted as better.
Most punter love their music and if they knew it could sound better they'd buy it judging by history.
So I think there is desperately a need to be able to duplicate tests that prove and can show we can hear something subjectively better.
In the meantime, a workable explanation while probably incorrect is;
the program material above the threshold of audibility reinforces the fundamentals and harmonics that are there within the audible range.
Now following on from this have you ever tweaked a channels EQ and and could hear change as desired only to discover you were on the the wrong channel. Own up on this one.
So one thing we do know for sure it is "all in the mind".
Lets not be too serious about it after all this is fun. It is fun I tell you. LOL