There were fewer stimulating media elements in the olden days. Kids have phones in front of their face constantly monitoring social media, games....all designed to deliver immediate gratification or reinforce anxiety inducing fears. No question that even calmer folks get agitated.It existed. Kids just didn't get the help they needed.
On the flipside; back in the day, it was probably easier for someone who couldn't sit still and pay attention in school, to just get a job that... didn't require sitting still.
That said; I didn't make my initial comment to go down the wormhole of analysis other than the off-hand comment about racing tendencies.