fwiw, in the US medical insurance does NOT include getting a dx for ADHD. Those parents who have gone through the process have paid $4,000 (aprrox.) JUST for the dx.
Then you have to pay a bit each month towards the meds - dd's cost me $50 per month. Luckily we can afford it.
The meds have to be signed for each time you pick up the prescription, which you have to order one month at a time from the doctor. You have to take the script to the pharmacy, (no automatic repeats) and, because it is a RARE (yes, please not that word) prescription, they don't have it in, so I have to wait a few days to collect the meds, at which point I have to sign three times to pick up and pay for it.
I work ft. The mileage from work/doc/pharmacy etc is probably about 50 miles by the time I've done the various journeys, and getting to the gp outside of my working hours isn't easy. As she is on an unusual (again - please note, unusual) medication, I have also had to appeal to our med insurance co. to get it covered, otherwise we would have to pay the full cost of it, which would be 100s of $ a month.
So, please, don't start thinking that the high incidents of ADHD in the US is because it is 'easy'.
And yes, in the past, ADHD or ASD people didn't get dx, the condition was discovered because the signs were there & scientific research shows what the cause is, but the symptoms have been recognised for many many years.
Watch the movie 'Let Him Have it' if you want to know just one example of how things were in the good old days before some quack invented it.
Then google the % of prison convicts with ADHD.
The % of school drop outs v college graduates.
In other words, do some reading and research before making your inaccurate assumptions.