Well it is certainly true that there isn’t a sharp and clear divide between ND and NT, so there is clearly going to be some debate in the diagnosis for a few people who happen to be around the border.
However, saying “ND means people’s brains are wired differently…. It’s all nonsense” is certainly highly debatable and probably incorrect and the “different wiring” and other physiological and chemical brain differences have been found in scientific research. If you want, I can dig out some reports/paper on this. The trouble is, the differences are ‘on average’ so doctors are not in a position to do a brain scan and use that to diagnose ADHD .
I have gone through the ADHD diagnosis myself. I have described some of it in another post. The clinicians that do it are highly trained and know how to cross check what you say. It’s not just a case of telling them that you are hyperactive and then they take your word for it. Apart from finding out your life story, they also look at other aspects of your health that are not included in the diagnostic criteria to see if they are typical of ADHD too. Eg I was asked about my periods.
Comparing significant disability due to ADHD with buying glasses and dying your hair is actually offensive. You only get an ADHD diagnosis if a clinician judges that you have significant and pervasive difficulties. ADHD is not a trivial diagnosis. It’s no coincidence that people with ADHD are often unable to hold down a job, end up with addiction problems or in prison, are more likely to be a victim of domestic abuse and are at far greater risk of a long list of mental and physical health problems eg depression, diabetes, migraine, ME/CFS etc