"The infrastructure of major cities like Atlanta, New York City and San Francisco were built using forced slave labor, convict leasing and on the other hand bridges and roads were built using strong union labor that still has to find their way to humanity under the law, so I guess both models are valid."
Just because something produces the results that you'd want does not imply that the model itself is valid. That's the justification that capitalists (or anyone with a distance from the act of production itself) will use and we do not have mimic that.
(Also please see my username)