I'd recommend that you talk to a few people with ADHD and see if they consider their disorder to be "the slightest deviation from the norm". It's clear from this article that doctors certainly don't see it that way.
Personally, I was lucky, as I was diagnosed as a younger age (Around 5th grade or 6th grade). Recently I took a college course on handling ADHD in college, and my professor also had ADHD, having had it for many years, struggling with it, and not ever learning about it until she was around 50 years-old.
I agree with those who say it may be over-diagnosed, but at the same time, it's frustrating to see people who have no understanding of the disease at all tell me that it's all in my head and I should just get over it and act like everyone else. Being a bit older, I've learned to simply shake it off and move on, but it tough being a kid struggling to do stuff that others seem to be able to accomplish no problem, and then be told that you're simply not trying hard enough and never get any access to education on ADHD and/or medication. It's no different then going up to someone with depression and telling them it's all in their head and to just stop it. It simply doesn't work that way, and pretending it does only makes those with the disease feel worse about themselves without helping them.
Any disorder or disease that requires a potentially addictive medication will inevitably have crooked doctors - this is seen as well with patients requiring Morphine or Codeine. This crookedness is a separate issue from the illness, and is not relevant in a discussion about neurobiology.
In the UK, I didn't have to pay anything for refills of concerta. In NZ, I only had to pay the GP who gave me a referral to a free psychiatrist for methylphenidate and dexamphetamine sulphate.
In both places, it has been a relatively long journey to get medication. They were keen to try to resolve my issues without drugs - it was about half a year between when I started seeing a psychiatrist and when they suggested medication.