Across the area that those that studied psychiatric medicine tell it to?
It's not about "some kids having shorter attention spans than other" any more than Alzheimers is "some people forget more than others I don't see the big deal".
Are you even aware of the impact ADHD can have on a person's life (persons, not "kids" alone, it's not some disease people grow out of)? Including (among the day to day impact) worse socio-economic outcomes, worse health outcomes, and significantly shorter life spans?
Except if dying younger is also "legitimized cheating" (sic). Perhaps people with ADHD do it to get a leg up on the competition.
https://www.thecarlatreport.com/articles/3096-reduced-life-e...
"Left untreated, ADHD can raise the risk of serious health concerns in adulthood. This includes a higher risk of diabetes, heart disease and shortened life span... which is why increased awareness and diagnosis is important."
But even if there was a confounding factor they miss, and "mere correlation", those problem will still be more present on people having ADHD (since they are statistically increased compared to the general population). The idea of ADHD as a fake illness and "they're just cheating" doesn't explain such outcomes.
Not to mention it's ignorant, with just media stereotypes about ADHD from 2+ decades ago to go on. ADHD is not just about "shorter attention spans" anymore that autistic people are like the Rain Man or Sheldon from BBT.
Some kids have shorter attention spans than others. Where does one draw the line between “personality” and “disorder”?