literally this. slaves with hard-to-replace skills were treated better, both individually and systemically. please don’t get me wrong, slavery was a horrid institution that represents the absolute worst humanity is capable of and there’s nothing that can happen to a person that is so awful that slave-owners don’t deserve it, but much like everything else in the western capitalist world slaves existed in a hierarchy. On an individual basis, house slaves were treated to “luxuries” that field slaves weren’t privy to, like being able to sleep indoors and even sometimes in individual chambers rather than communal housing, and greater access to the amenities of the house when they weren’t being used. On a more zoomed out level, slaves that came from areas with unique skills in their culture were granted much more leeway in preserving that culture than slaves that were used for so-called “unskilled” labor. One well-known example is that of the Gullah-Geechee people. Because they came from a people in Africa who knew how to grow rice, a process that is idiosyncratic compared to other crops and involves a lot of domain knowledge, they were mostly forced to work in rice paddies in the coastal lowlands of the Carolinas, Georgia and Florida. This let the Gullah-Geechee people preserve their heritage and language better than other slaves because their community wasn’t broken up at the whims of the masters. Only Gullah could work the rice paddies so the rice paddies were full of Gullah teaching other Gullah their language and culture. After slavery was reduced in America, those same rice paddies became the livelihood of those same Gullah people, who tended to form insular, rural communities that are still alive to this day.

So yeah, they’re arguing that slavery taught black people skills they could use to make slavery a bit more bearable. That’s the freedom that markets offer: slavery with amenities.