“The areas of the nation that are right now the hotbeds of Unionization, in those days would have regarded slaves as “scabs” who would take the bread out of their own mouths.”
Hmmmm….
“Planters often hired out their slaves as carpenters and other tradesmen. European shipwrights taught slave apprentices, who became skilled shipwrights themselves and trained other slaves. White artisans, however, complained that slave artisans were too prevalent in South Carolina, depressing wages and making jobs scarce. In 1744, Andrew Ruck petitioned the Carolina Commons House of Assembly for relief from the large number of slaves “employed in mending, repairing, and caulking ships. . .and working at the Shipwright’s Trade.” In 1751, the Assembly placed a tax on imported slaves, and one-fifth of the revenue was used as a bounty to encourage shipwrights to move to South Carolina.”
https://www.scseagrant.org/rise-and-fall-and-rise-south-carolinas-maritime-history/
About 12% of American workers are unionized. So where are these flaming hotbeds?
Prior to that, slavery was on the wane, and prior to that they did use them for other things because those other things were more profitable at the time. After cotton became more profitable, the vast majority of slave usage was for that purpose. Yes, there still existed slaves dedicated to other work, but this was a teeny tiny fraction of slavery at the time.