This is such a ridiculous "wannabe the case" notion. Isn't it human nature to work enthusiastically at optimum levels without compensation? Of course not. This is when blacks got the reputation for being slovenly. They performed minimally and rarely earned their keep. This is precisely why sharecropping came about. They had to institute sharecropping so they would work just hard enough to produce their own food.
The foremost authority and historian for the the US during the 1800's was De Toqueville and he clearly documented the realities of slavery during this time. He noted the stark contrast between the work ethic, industriousness, and ingenuity of free Americans as compared to the slaves. He also attributed it to the complete lack of any motivation to produce due to the absence of the capitalistic motivations free Americans enjoyed. No government interference and free Americans solved issues on their own without any expectations for government involvement. Something De Toqueville made note of in large contrast with their European contemporaries too.