Unbelievable...

[Big_Japan]

It may seem counterintuitive, but forced labor is not the most economically viable mode of production anyway.

It's far more profitable for a master to simply defray a small part of his slave's living expenses and then release them into the jungle, trusting starvation will ensure their return, than it is to provide cradle-to-grave care and constant security. Overt slavery increases the sense of alienation from labor product, which affects morale which affects productivity. Simply renaming slavery to something else and turning the ownership of slaves into temporary contract, with 'freedom' to re-enlist with another master anytime instead of a lifetime commitment results in a multitude of effects that ultimately benefit the bottom line.

Did you seriously think we got rid of slavery because of some great moral-ethical leap forward? Urbanized North had simply found that slavery was outmoded for its economic model and it could benefit from the propaganda effect of being "free" without net economic loss, whereas the South's agricultural economy had not quite reached that tipping point (although slavery was in decline in the South at the time).