There are plenty bosses like this in Germany, which doesn't have as much of a history of slavery.

I'd wager that when looking at countries with roughly the same level of industrialization, whether humans view fellow humans as something more than mere resources is linked to a certain set of attitudes.

I'd guess that reduced working hours are positively correlated to pluralism and pacifism, and perhaps negatively correlated to religiousness.

The more you think that life ought to be lived a certain way, the more likely you are to see work as a savior from straying from that way.

Looking at countries that have severely mistreated minorities, natives or remote people might also reveal a correlation, the more so the less this is part of the public consciousness.