In a drab office building near a slum on the outskirts of Nairobi, Kenya, nearly 200 young men and women from countries across Africa sit at desks glued to computer monitors, where they must watch videos of murders, rapes, suicides, and child sexual abuse.

These young Africans work for Sama, which calls itself an “ethical AI” outsourcing company and is headquartered in California.

Sama says its mission is to provide people in places like Nairobi with “dignified digital work.” Its executives can often be heard saying that the best way to help poor count…