Can't speak about all cases but many if most I have seen have no difficulty concentrating on what they want to concentrate on.
“many if most I have seen have no difficulty concentrating on what they want to concentrate on.”
That’s been my observation, too. Seemed like a method to manipulate parents, teachers, co-workers, etc., into getting a pass on not doing what they didn’t want to do. When they were doing what they wanted to do, focus and interest was fine.
When we were kids, if we had pulled an “I have ADHD so I must be coddled”, we’d have been cured within five minutes.