These tests "prove" nothing except that the people involved did not hear a difference, not that others wouldn't.
Agreed. It proves absolutely nothing at all.
I think we can also all agree that there must be some (even if ever so small) difference and that the output of some gear may be a great deal more sensitive than others to a very small difference of this type (a speaker with a low impedance point of 4 ohms, for example, on the end of a 50 foot cable).
However, before we jump to conclusions, where are the blind tests that "prove" that there are "some others" who can indeed hear the difference on those high quality very expensive cables? (...and then logically what type gear specifically requires careful attention to cables?)
And I am not referring to the Misleading Monster cable in store demo which you can read about on Roger Russel's website and where a difference is very obvious.