They are plantation owners which means they’re gonna need people to work in their land and most plantation owners owned acres and acres of land which was clearly a lot of work for one man and so they needed more men to work on it and so they got slaves. (it also somewhat showed that they had a lot of money since they can buy slaves.)
Since they were farmers, they need the slaves to collect the crops and to plant more. Most of the time, they lived on large acres of land so it was more than a one man job.
Corporate managers who fail to give due consideration to the rights of employees and other concerned groups in the pursuit of profit are treating these groups as means to the ends of stockholders. This is unjust according to the rights-based ethical framework.