It doesn't. People working today's farms (corporate and self operated) AFAICT put in more hours than their 1920s analogues as much more of their time is consum

It doesn't. People working today's farms (corporate and self operated) AFAICT put in more hours than their 1920s analogues as much more of their time is consumed by the other parts of the business rather than working the fields component. They do create significantly more for their time, true. But this idea that exists that automation has given us more free time isn't quite borne out by the evidence.