Environmental factors can certainly exacerbate mental disorders like ADHD, but they are not the sole cause. Just because there are countries that don’t recognize mental disorders as well as others just means they are not up to snuff.
What you described in your second paragraph is just being bored. Not being able to focus on uninteresting topics in a poor environment is standard for most people.
I’m going to support what the person you responded to said, you don’t know what ADHD is.