[Edit] ok, yes, please. I get that i missed the k in kcal. The point stands. Biological training is massively more efficient, even when you forget to multiply by 1000
In general, saying that biological systems are "wildly efficient" is... wildly wrong. Some biological processes are optimized by evolution... most are not. There are no bicycles in nature.
Doesn't pass the smell test. I think I could push an electric car at least a mile a day if that's what I spent most my extra calories on. If I did that I'd surpass its range in well under 2 years, much less than my lifetime.
A human consuming 2000 kcal/day (conservative estimate) uses about 2.32 kWh per day. Over 75 years, that's roughly 64,000 kWh.
If the true, total cost of a machine to perform some task is less than a person to do the same task, then the machine should do it and the person should move to do what the machine cannot. This means more energy is available for everything else, living included.
Given that the human brain takes much longer to "train", I wonder how the energy efficiency pans out — comparing the two.