> 1. mental health patients are extreme in their dysfunction, never common.
I agree with what you're saying, but the US does have a problem of over-testing, over-diagnosis, and over-treating illness. Not just mental ill health, but everything.
In the US about 10% of children have ADHD
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3489818/
> Based on the Heath Resources and Services Administration's National Survey of Children's Health, the percentage of children aged 4–17 years diagnosed with ADHD increased from 7.8% in 2003 to 9.5% in 2007, representing a 21.8% increase in just 4 years (Centers for Disease Control and Prevention 2010).
An estimates 3million US children take stimulant medication:
> Experts estimate that approximately 60% of children with ADHD are treated with prescription stimulants (Center for Disease Control and Prevention 2005a); therefore, approximately three million children in this country take stimulants for problems with focusing. At the same time, many studies have revealed the numerous adverse effects associated with prescription stimulants when they are used inappropriately.
These numbers are a bit worrying, especially if medication alone is being used, and it's not provided as a package of bio-psycho-social treatment.