The abolitionist and former slave Frederick Douglass had this to say on the subject of wage labor[1]:
> [E]xperience demonstrates that there may be a slavery of wages only a little less galling and crushing in its effects than chattel slavery, and that this slavery of wages must go down with the other
From Wikipedia[1]:
> Douglass went on to speak about these conditions as arising from the unequal bargaining power between the ownership/capitalist class and the non-ownership/laborer class within a compulsory monetary market: "No more crafty and effective devise for defrauding the southern laborers could be adopted than the one that substitutes orders upon shopkeepers for currency in payment of wages. It has the merit of a show of honesty, while it puts the laborer completely at the mercy of the land-owner and the shopkeeper"
> [E]xperience demonstrates that there may be a slavery of wages only a little less galling and crushing in its effects than chattel slavery, and that this slavery of wages must go down with the other
From Wikipedia[1]:
> Douglass went on to speak about these conditions as arising from the unequal bargaining power between the ownership/capitalist class and the non-ownership/laborer class within a compulsory monetary market: "No more crafty and effective devise for defrauding the southern laborers could be adopted than the one that substitutes orders upon shopkeepers for currency in payment of wages. It has the merit of a show of honesty, while it puts the laborer completely at the mercy of the land-owner and the shopkeeper"
[1] https://en.wikipedia.org/wiki/Wage_slavery#History