I tend to agree with you about there being a distinction between unpaid and paid slavery, however I am not sure it's as useful or as clear a distinction as you imply.

For example - one way in which slaves can be held captive is by having them work in a remote place where they don't have the resources to travel across the space between them and the rest of society - e.g. A camp in the desert, or jungle, or a plantation on an island.

It is not clear why this kind of captivity is distinct from the captivity that arises when the barrier to cross is economic and social rather than physical.

If people are being used as laborer a in a position where they cannot accumulate enough resources to leave, what difference does it make what kind of wall keeps them there?

Slaves could walk away by 'purchasing' themselves. Or by escaping and not getting caught. Or by being freed by masters/authorities for various reasons.

  > "And don't bother to make the argument they can't walk away for economical reasons. It's still a whole different thing."

This is the key thing. Slaves in the past couldn't walk away for economic reasons as well (i.e. many of them couldn't purchase themselves and become free). Also, today, if you're a US citizen, in order to renounce citizenship, you need to have another citizenship, which usually takes many years to get. So, it's very difficult to escape US Taxman, which takes half of your income (i.e you work half of the time for the Taxman).

Slaves today are little bit more free than those in the past. But, not by much. Again, you're nitpicking with the term 'slave'. It's like saying 'cats don't walk', because they don't walk as humans. You don't have to walk as a human to be labeled as 'walking'. Likewise, you don't have to be literally in chains to be labeled a 'slave'. But, people who benefit from slave labor, like the author of the post, don't want the term 'slave' be used, because it would expose him a scumbag.