This is owing to his suffering from something emergency room doctors talk about when they think that we cannot hear them. They would look at him and chuckle to themselves about how John Patterson presents with fecal encephalopathy in the hopes that a mere dentist would not realize that they think he's got shite for brains. The same dunce who thinks that hormones and not his being an insensitive, entitled clod who won't admit that his wife feels overwhelmed and underappreciated explain why she's always out of sorts looks at what only superficially looks like the boundless energy of a child at play and thinks to himself "CHEE!!! Why can't I harness all that wasted energy for something useful?" What he doesn't want to admit (owing to a fear that admitting that his decisions are arbitrary and self-serving, his parenting style idiotically authoritarian and his manners petty and immature would mean that he'd lose his standing in the community) is that not only does a small child tire easily, being bellowed at because he does the expected crappy job of washing Daddy's ride is a means of destroying his work ethic.
We can lump this in with Elly's shaving sheets as the sort of false practicality inflicted on the world by a muttonhead who doesn't know what planet he's on seven eighths of the time.