I blame it on movies and TV.
It is a flaw in the system, given the prevalence unchecked.
If we're using legal slavery as an example, countries that abolished slavery early ended up being more productive because employees actually want to work/innovate/create quality goods. By hiring slaves or treating your employees like crap, you're voluntarily specializing in the low-end of whatever market you're in, because your employees don't care about the product.
That's rarely the most profitable move unless you have a monopoly or a commodity good, like the examples you've provided.
We're doing this experiment right now in Canada by importing millions of temporary foreign workers/international students to work in slave-like conditions. If ruthless toxic slavery worked, we should be making more money. In reality, our GDP/capita has dropped continuously since 2019 indicating we're actually less profitable per person.