Poverty isn't to be identified with slavery, true enough. It would be quite possible to have slaves kept in luxury, but they'd still be slaves.

But the attitudes that underly a slave system - the ability to draw a line between ourselves and other humans that means we see them as less than human, that still exists inour society, and that does relate to the way people can shrug off appalling inequality of all sorts, as if it wasn't something that concerned them.