It probably wouldn't be a good idea because demand would collapse, and there's no work without customers.
This is actually why economics is called the "dismal science", it's not because everyone hates economists, a slave-owner gave it that name because he was mad economists didn't like slavery.
Given the low income/wealth of the people doing the work, that's not a convincing argument.
There's a reason why overall income didn't really go down in 2020 (and even increased in some places), and thats because poor people don't actually make that much money, nor do they provide any significant value.
Poor people’s income went up in the US, and the poverty level decreased, because we actually did a proper economic stimulus for once instead of an undersized one like in 2010.
Adding to the previous comment, slaves also work much less effectively than employees because slaves have no incentive to try hard, since either way they will stay slaves.
Pretty much this... incentives matter. But if you’re a slave, what’s your incentive to work harder?
As for literature backing this up, Adam Smith in Wealth of Nations talks in detail about slavery in the American colonies.
He gives examples where slavery was only viable in the southern states where they grew tobacco. Maybe one of the reasons why the South were so opposed to the end of slavery vs the North where slavery was expensive
This is actually why economics is called the "dismal science", it's not because everyone hates economists, a slave-owner gave it that name because he was mad economists didn't like slavery.