Its not just usa but all the western capitalist nations. The goal is to maintain workers at the lowest cost. Drugs are cheap to produce. If they make workers slightly less effective by deadening their senses it just means they will not look in to the real causes of their suffering. There are no shortage of unmedicated workers to take up the jobs that require a clear mind. If they make people die sooner it means less old age pension payouts.

ADHD symptoms are well proven to be treatable in most cases by proper medication. They also help children with ADHD have their brain develop to be far closer to a neurotypical brain, causing a cessation in distressing ADHD symptoms in adulthood sometimes allowing them to be able to come off medication entirely.

ADHD medication, prescribed properly and titrated onto under guidance of a specialist doctor also is not addictive and easily weaned off of.

ADHD is a disability under capitalism, and even under socialism can cause massive issues and certainly can be disabling even under a fairer economic system. We will need to move to a much more accommodating system of work that might still only get an unmedicated person with ADHD up to like 80% as efficient over long stretches of time (short term analysis is pointless because most people with ADHD can completely outperform neurotypical people while a task is novel and interesting to them). It is a tiring neurotype to have as you desperately want constant stimulation and newness that is just impractical to provide in most cases. Not to mention its higher likelihood of co-occurence with Autism that also makes the person crave structure and routine as well as novelty in the right doses, which just throws a big spanner in the works for accommodating them.