Does ADD exist, as a chemical imbalance that can cause a reduced attention span? Possibly, even likely.
Do I know a vast number of people diagnosed with it? Yes, nearly as many as I know diagnosed with "CLINICAL depression" (in which they always emphasize that first word as though proclaiming knighthood). And yet... not a single one of those people has ever had a MEDICAL test done that checked any hormone/chemical/neurotransmitter levels in their brains. They underwent certain COGNITIVE tests--books, questions, puzzles, and so on.
My problem isn't the existence of vague disorders like this. My problem is how they are diagnosed and how they are TREATED.
WHY PARENTS LIKE THEM:
My kid is misbehaving or getting bad grades. I don't know what's causing it, but I would rather not think that it's because there's something I could be doing to help and I'm not doing it... or that there is something I'm doing that is harmful. So, if there's a doctor will to tell me there's a pill for that, I'll take it. (NOTE: I will also buy pills that promise to make me skinny and buff without making me face my bad habits in those areas, too)
WHY TEACHERS LIKE THEM:
(NOTE: I am a teacher, and of middle school kids) Johnny is misbehaving and disrupting class, drawing a disproportionate amount of my attention and the class's time. We've called and called and called Johnny's mom, but she just won't do anything substantial about it. And we are not empowered by the state to take necessary steps to fix the problem in any way. So, instead, we will GLADLY sign on to give the kid a pill. Not because it will help him, but because it will get him OUT OF THE WAY so we can teach the dozens of other kids that are there.
WHY KIDS LIKE THEM:
If you tell me "You know, this ATM machine has a special code that you can enter. It will give you money even if your account is empty," I'm going to be SEVERELY tempted to use it. And I'm a grown-ass man! A mature, morally-okay adult with strong principles.
In the THOUSANDS of years that human society has functioned on this planet, kids have NOT CHANGED. They have always been selfish little buggers who will do whatever they can get away with--because that's our animal nature, nothing more. When you tell a child, "The reason you do these things, and can't do those things, is because you have this disorder," you are giving the child information well beyond their maturity to handle. You just gave that "ATM code" to a TWEEN CHILD.
Even children with LEGITIMATE and very PROMINENT disabilities (cerebral palsy, asthma, diabetes) will have a tendency to go through stages in which they USE these disabilities for extra attention or to get out of something difficult. It's HUMAN NATURE. But at least with THOSE, there are measurable ways that we can verify the problem--and you can eventually identify when a child is "bluffing," and they'll usually work themselves out of that stage.
But when it's something as nebulous as ADD/ADHD? It's a license to shirk work and cause disruption, and since it's classified as a "manifestation of disability," you can only get into so much trouble for it--if any. KIDS ARE KIDS, and they will EAT THAT SHIT UP.
WHERE WE GO WRONG:
Treatment. Not just how we treat the disorder chemically, but how we treat the kid with our expectations.
For instance, if you know your car's speedometer is always 5 mph high, that doesn't mean "Hey, that means I get to drive 5 mph over the speed limit!" It means YOU have to pay attention to YOUR speed a little closer, so that you're still following the same rules as everyone else. EVEN IF YOU CAN'T GET THE SPEEDOMETER FIXED, EVER. It will always be your responsibility to compensate for that.
Or what if you break your knee, and you've got a leg cast? Yeah, while it's healing you keep off of it... but eventually, you've got to put weight back on it, or it'll atrophy, or even heal wrong. You don't just write off the weak leg and use only the strong one forever... or it'll never be useful again. And when you use the weak leg, it will be HARDER, but you HAVE to do it.
So, the fact that a kid has trouble paying attention doesn't mean we just EXPECT him not to pay attention. It means we demand he try EVEN HARDER. It's not a license not to work hard, it's a MANDATE to work HARDER.
But what about medication? Absolutely useful! They help a kid get to a point where they can learn how it FEELS to pay attention. And then you know what? They can learn how to create that feeling for themselves, bit by bit, and phase out the chemical assistance. Medication is meant to be a CRUTCH, not a PROSTHESIS.
So, yeah, nutshell time: We love ADD/ADHD because, as a modern culture, we accept REASONS for EXCUSES and stop working toward SOLUTIONS.