Show me a few adults who developed perfect pitch after childhood, and can PROVE it. Otherwise, *yawn*(P.S. I mean the kind of proof that scientists or law courts would accept -- utterly rigid and harsh.)
It is usually tested through naming, and it is defined through naming. "Perfect pitch" means that you recognize a pitch as distinct, and possibly, that you can produce it. You can see that an apple is red without having the word "red", and the fact that you cannot come up with the word "red" does not prove that you cannot see this as a distinct colour. If you do have the naming test, then according to what tuning? A=440 alone?The bigger question is how is it useful? I ended up developing something like that, through an exercise that was meant for something else. I didn't find much use to it, and I didn't push it any further. Btw, I was in my early fifties.
Why would anyone want perfect pitch?It's close to useless for musicians. It' more a tv thing than anything else.