I am really wondering how much of this is your daughter and how much is this leader. Anyway, the reason you may get the sense that some adults believe "that ADHD is not real and just an excuse for poor parenting" is that that's exactly
what some of them believe. Aggravating this is that things like that idiotic Psychology Today piece called something like "French Kids Don't Get ADHD" keeps floating around on Facebook like a turd in a swimming pool. Never mind the PT has published two rebuttals to the article. It reinforces people's preconceived notions and prejudices, so they suck it right up. France actually has notoriously regressive ideas around developmental and behavioral disorders (they were still treating autism with psychotherapy in 2012, and may still be for all I know).
I started a blog for parents of kids with oppositional and defiant behavior. I don't think anyone reads it, though, because I don't publicize it outside the support groups I use. I'm just not sure I can deal with the ignorance and bigotry I'm likely to encounter if it were more public. Here's an entry on parent blaming (and about half of ADHD kids are co-diagnosed with ODD) that is written to ODD, but a lot of it applies to ADHD, too.
Maggie (in VA)