I never needed to be beat in public--I knew if I did act out, either one of my parents would smack me or my brother as soon as we got home. Even if my dad was tired and was asleep (since he worked night shift), my mother would wake him up to allow him to give us a smacking for acting like a brat. As a result, none of us acted out in public.
True, there are some real cases of ADHD, but that's a slim to none case. A professor I had a while back studied ADHD, and one of the studies he mentioned he conducted linked bad case of parenting and insuffiecent punishment to ADHD. He mentioned that there was a huge positive correlation of the two. Of course, as soon as he released the study to be peer reviewed before getting it published, he got a shitload of reviews that said things like, "It's not the parent's fault! ADHD is a biological disorder!", "Parents are better today than what they were in our time!", etc. etc. Ugh, even researchers are so close-minded now-a-days.
As the poster mentioned, ADHD is just a label so that the parent can take some of the blame from their own bad parenting off of themselves.