Thanks for your question. We need to get one big thing out of the way here before we can go into the nuances:

Nobody in the United States treated the people they enslaved well because slavery as a set of social and labor relations was built on a foundation of theft and violence, both physical and psychological. “Equality” could not coexist with slavery because slavery insisted that people could be property. The only way for a slaveholder to treat an enslaved worker as an equal was to free them.

Slaveholders had the power to sell anyone they held in bondage, often children (50 percent of purchases or sales of people in the United States involved splittinge up a family, itself a “kind of murder” as separated family members often never saw each other again). The slaveholding states did not recognize the rape of enslaved people as a crime. Slaveholders had effectively limitless latitude to inflict violence on the bodies of the people they enslaved. In colonial Virginia, courts reimbursed slaveholders who murdered slaves if they could prove that they did so in the course of “disciplining” them.

People who are working because they want to are, often, quite dedicated workers, producing good products with efficiency because they want to be producing them efficiently. This is something that some anti slavery advocates argued in the years leading up to the civil war. Slaveholders did not see that as necessary, both because they often thought of the people they enslaved as subhuman, and because a regime of torture and terrorism had made them some of the wealthiest people on earth. Assuming that the only thing on slaveholders’ minds was a singleminded and rational pursuit of efficiency forgets that they were fanatically dedicated to an ideology of white supremacy in defense of their position of power and privilege in a slave society.

All that said, slaveholders did try to inspire loyalty in the people they enslaved, through the warped lens of an ideology called paternalism. Paternalism developed in the 19th century as slaveholders found themselves increasingly under attack from an ever growing number of people who saw slavery as a political liability and moral evil in America. In response to the criticisms of anti slavery advocates, slaveholders insisted that they acted as parental figures to childlike slaves, who looked upon them with love and devotion. Slaveholders, they said, were a civilizing force on savage African people, correcting and disciplining them when they acted out and rewarding them when they behaved well. If not for slaveholders, they said, black people would live in a state of animalistic barbarity. This was an ideology, you might be able to guess, that still gave slaveholders free reign to overwork and torture the people they had enslaved, though it convinced many that the loyalty of people they held captive and forced to labor could be earned (what the historians Eugene and Elizabeth Fox-Genovese called a “fatal self-deception).

How did slaveholders try to earn loyalty? Not by working side by side with their slaves as equals (though small slaveholders who held fewer than 10ish people usually did so by necessity). They did so often by giving “gifts” which ranged everywhere from hand me down dresses to favored domestic workers to the day to day clothes worn by field hands (all of these gifts acquired by the fruit of the slaves’ labor). Slaveholders might “grant” enslaved workers a day off each week to use for their own purposes (though this was just as often a settlement reached through uneasy negotiation). Slaveholders might attend weddings (which had no legal weight) or funerals for enslaved workers on their plantations or neighboring ones. All of these acts, in the slaveholders eyes, inspired love from their slaves by reinforcing the brutal inequality at the root of slavery. It was intended to do the opposite of treating enslaved workers as equals.

Slaveholders were often rewarded by bright and smiling faces from the people laboring in their households. Tears when they left their properties for long trips and joyous welcomes when they returned. This helped assure them that they were good people who fit the paternalistic ideal. But, the last days of James Henry Hammond, a large South Carolina slaveholder and pro slavery fanatic, tell a different sort of story. In the last days of his life, as Confederate defeat in the Civil War seemed more and more likely, and as emancipation seemed more and more certain, the slaves stopped smiling at him. They stopped following his orders “cheerfully” and started responding to his orders with scowls. Hammond was a smart guy, I think in his last days he was forced to realize that when freedom was so close, the people he enslaved no longer felt a need to engage in the humiliating charade they’d been forced to endure when Hammond and the rest of the slaveholders had been more secure in their power. They no longer felt the need to pretend that they liked him, that they respected him, that his “gifts” to them which he could only buy with the products of their labor were valued and appreciated. So they let him die knowing the truth. And this was the truth on all the plantations in the American South before the civil war brought an end to slavery.