The author is French, the story in France, and the slaves are Roman.

No shortage of French slavery in the New World. Just ask anyone from Louisiana or Haiti.

Maybe it’s in the movie adaptation, but the scene of their “freeing” is pretty clear about its point.

Oh sure. You can find all sorts of period critiques of industrial capitalism as slavery with extra steps.

But the notion that people would volunteer to return to bondage really undersells how hard plantation overseers and state police in slave states had to work to keep them there.