This was a really interesting podcast. Slavery (at least the American version) was essentially a result of crony capitalism and may not have been sustainable without special government favors.

Years ago, I think in the book 1493, I read about how certain elements of the Virginia charter made it almost impossible to work the land productively with free labor alone. IIRC, every free person was granted more land than one individual could work, so slave labor was the only legal way to efficiently operate that economy. Obviously, that's nothing like a moral justification for using slave labor, but it's an interesting economic detail.