isn't this wishful thinking? you're saying that nobody would own slaves because it's bad.. but you know what? the past is an indicator of the future, and throughout most of mankind's history, we've had slaves. in a dystopian society, which is what would happen under a worldwide anarchist government, i'm sure the few bad guys wouldn't mind owning slaves.
Slavery is built into human nature and it's exactly the state which is constraining it. But the primary reasons for this are not empathy and all other such things but rather economic ones. The present level of technological development makes slavery obsolete because under present conditions it is an inefficient form of organizing human labor...
Take any primitive society and they beyond doubt would have slave labor... Even ants have slaves!
The reality is that near slave like conditions still exist in some cases in West. Often even with apperance of everything being right. And the victims might not even understand they are slaves...
I understand that slave like labour has been used atleast in some restoraunts here. That is for labour intensive stuff that can't be always automated.
On other hand for many things it's not just cost effective anymore. Farming, mining and so on, much cheaper to get machines...