People who are paid to do work they don't want to do don't believe in the existence of people who would do work they don't want to do for money.
(In reality the distinction between slave and employee is blurred over thousands of years and it's hard to use our words to talk about their setups. It's likely that both slave and non-slave labor (taking slave to be unpaid coerced labor) was used; just as our society uses both, either openly or discretely.)
(In reality the distinction between slave and employee is blurred over thousands of years and it's hard to use our words to talk about their setups. It's likely that both slave and non-slave labor (taking slave to be unpaid coerced labor) was used; just as our society uses both, either openly or discretely.)