ADD/ADHD is thought by many to be a legitimate psychological learning disorder. However, it was once also widely believed that the world was flat. The "disease" is often characterized by a short attention span, or what people used to consider lethargy/laziness/stupidity. Methylphenidate is often used as a treatment despite a lack of any proven defects with in the brain.
Society views the symptoms of ADD/ADHD as unconducive to productivity and naturally it labels them as a disease. Leading children to believe they have a psychological disorder from a young age and convincing them that their symptoms are unnatural perpetuates the idea that they have special needs. Just because you don't do well in school it doesn't mean you have some life changing disability.
"But wait, thats only for people who think they have ADD! I am part of the minuscule 16% of people that actually has it, you arrogant pig-whore! I'm special."
16% of 300 million, the population of the U.S. is still an absurdly large number. Even more absurd is the idea that because you don't like working hard in school like every other kid that you deserve extra attention.
Don't buy into the idea that falling short of societal expectations is a disease and consider people with real problems like people with Leprosy, HIV/AIDS, Restless Leg Syndrome, Pre-mature Balding, Spilled Milk, and Ebola. You want to hear about real problems? Talk to a midget, those guys are fucked up.
ADD kid: "Oh man, reading books is boring. Why hasn't my teacher taken my needs into consideration? I hate work."
Unbiased Scientist: "Well you brainless sheep, all you need is a punch in the throat and maybe to stop blaming your problems on made up diseases."
ADD kid: "What? I wasn't listening because I don't have to, I have ADD/ADHD"
Unbiased Scientist: "Go beat up some queers or whatever it is you youngsters do these days. You don't actually have any problems."