Only fear and pain could motivate labor from people who otherwise had no incentive to work. Many slaves resisted by refusing to work or by blundering at their tasks, so they would receive lashings, and salt would sometimes be rubbed into their wounds. Some would have their faces branded for identification, or have their ears lopped off or their noses slit as punishment. And to prevent fleeing, their hamstrings would be cut or a foot severed. The worst treatment was on the West Indian sugar plantations, which were highly labor intensive. Only small children and a few aged and invalids escaped the regimented and demanding conditions. No wonder the great planters were always in fear of slave rebellions.
Slavery was a test of wills, really, that favored the slave masters and their draconian slave codes. Some slaves managed to escape and hide away in "maroon" colonies, but many ended up killing themselves rather than endure the treatment they were receiving.
Even white slaves were abused. Elizabeth Abbot was beaten to death so horrifically that a witness saw her "body full of sores and holes very dangeroulsy raunkeld and putrified both above her waste and upon her hips and thighs."
If we still had slavery today, masters and slaves would still be engaged in a test of wills, as little or no personal benefit comes to the laborer. Many blacks today are fat and happy on the "Democrat Plantation," but at least they have some say in that, and no one is torturing them. They are certainly better off now.