> for basically nothing in return

Basix protection and basic law? Sure, far from an ideal model we would have in mind today, the comparison is against a completely "free" society as in much much longer ago.

> must sharecrop at least some of their land, and on sharecropped land, extraction rates are on the order of 50% (for basically nothing in return).

Uhm... so half of an unknown number? That's also an unknown number then, and the very concrete "50%" means nothing.

I'm only complaining about the TL;DR, the original article is great. After reading it, I think there is no good TL;DR possible. There is too much to consider, actually reading that link seems and unavoidable if one actually wants to know. Would someone in two hundred years looking at average income in the US today as the one or two sentence TL;DR have a useful picture of what life is like in the US today?

The rate floated around a lot by time period and domain, but 50% is a good approx figure.