[almavi]

My first thought was: "Oh, great! If slave labor is not efficient anymore there will be no more slave workers in the world". On a second thought (and based on our history), that probably will be true, but only because people that today are working just for a plate of rice will starve to death.

[jaggederest]

It's fairly clear (and distasteful) that economically, slave labor is inefficient because you have to feed/house them or you lose the 'investment'. In contrast, you can pay someone well below a living wage with virtually no penalty. This is why so many people at the low end of the labor pool have multiple jobs.

[Quarrelsome]

the sad truth is that slave labour needs no startup cost beyond a fist.

[kevinr]

Fists ain't cheap.

Slaves are capital, and, like all capital, acquiring and maintaining them has nonzero cost.

In the antebellum American South, some tasks like ditch-digging were sufficiently hazardous that a plantation owner would rather not risk their investment in their slaves, and so would hire Irish ditch-diggers by the day, as the plantation owner would be out less money if they died while digging the ditch.