Do you have links or suggestions for stats about “hours worked per bushel of grain etc.”? I’m interested in this area.
something like this: https://sdgdata.gov.uk/2-3-1/
look at the table of labour productivity, it has been growing consistently and has almost tripled between 1973 and today
But it is a well studied topic, with much more than 5 possible explanations offered for it.
I personally think the whole thing is a bit of a nothingburger that comes about as a simple consequence of how we measure productivity, which is via measuring how much money is paid to people. And since monetory / fiscal policy more or less ensures that all the people are always paid something for something, productivity growth is manifested as invention of new service industries, from personal trainers to dietologists. In other words, our productivity metrics mostly measure hours worked.
Better metric would be how many hours worked it takes to produce a ton of nickel, or a bushel of corn, or a typical family car. And those number have been going down consistently, suggestive of strong productivity growth and no paradox.