I'm curious what you would change about (Western?) society to make ADHD manageable like it apparently already is in "many countries," in concrete well defined terms. Not sure how society could negate the emotional regulation issues that frequently come with ADHD. I would also emphasize there's a distinction between "a society where people with ADHD can function" and "a society perfectly suited for people with ADHD."
I'm sensing that ADHD is a label thrust upon you, and if you feel you function fine without any sort of treatment it's probably not accurate. It's also now occurring to me how hilariously easy it would be to troll any sort of mental health issue. Depression isn't a disorder it's just SADNESS coming from MODERN SOCIETY and we just need to uncheck the CAUSE DEPRESSION box in society's configuration.