The idea that slaves built much of anything is preposterous. I mean, I've known plenty of people who worked as helpers or casual laborers at power plants and automobile manufacturing facilities and shit. They do things like sweep up after the electricians and mechanics and put out snacks for the safety meetings. They are modestly compensated now, but certainly the successors to the slaves in the role they play. If they tried to point at a library full of books or a lot full of shiny new cars and say, "I built that. Yeah, me" people would laugh at them.

Now, if they were to say "Ford didn't really pay me enough" or "Georgia Pacific had shitty benefits," well, OK- that may be valid. But you did not "build" much of anything at all.