Although driving may also tap into it, the issue is mental burnout. Cleaning or eating doesn't take mental capacity, thinking does and that is in short supply (as the article notes, study show there's about 6h of good thinking per day in an average individual). Yeah might be able to "productively" work 80h/week if half that was cleaning the toilet... why?
> I could certainly do my primary job for 40-60h/wk productively and then spend 20h/wk doing meetings with users, conferences, etc.
No, you might think you do.