Slaves weren't cheap, but the income and wealth inequality of those times was incredibly larger than today. In many jurisdictions slaves actually were just property, not people. Wealthy slaves owners still could kill slaves just for fun, without feeling much financial loss. Like today someone could buy a Tesla and then decide to burn it.

(Though we should recall that the rights of slaves and whether slave-owner could be prosecuted for manslaughter obviously depended on era and jurisdiction).

I find it astonishing that people compare modern-day income equality and the position of the poor in our time, in the Western world, to that of historical slavery (slavery in United States, or slavery in other slave-based economies in the New World prior to 19th century, not to mention slavery in the Old World which continued officially well into later half of 20th century).

In the West, no one is legally killing, whipping or dismembering the poor workers for not being obedient. Even the poor are still free to leave a place if they find life there unsustainable. Modern-day comparisons to "slavery" typically involve something along the lines "you are expected to do something in exchange for money that is given to you and you feel unpleasant about it".

It just doesn't compare with the actual, terrible injustice of real slavery.

You do understand that this is basically the argument that slaveowners used to justify continuing slavery in the 19th century?

It would be a mistake to say I'm advocating slavery by making this comparison. The slave to a master is just like an automobile: you have to put gas into it to make it go. Turning a human being into something the equivalent of an automobile is an abomination. But I don't really think wage slavery is really all that different at the end of the day. My point is both are abominable.

that may have not been your intent, but it does reveal the error in your thinking. You may call both abominable, but do you not see the fundamental reason why one is categorically worse than the other? If not then you are doomed to advocate for the very problems that were the root of the atrocity of slavery, just in other, possibly more cryptic and slyly paternalistic forms.

Except that no one is justifying slavery, it's just the opposite.

You know it is a good time to re-think the current economical distribution when the slavery looks like a valid alternative to the status quo.

The difference between slaves and workers is that dying or becoming too wounded to work is an expense, for slaves.