Why should we care and how tough Amazon has it, if ignoring that threshold really means "yeah, we're fine with some more poverty-while-working in the society"?
Correction: keep some people out of poverty.
Higher prices -> fewer purchases -> fewer parcels being delivered -> fewer drivers required.
Drivers who were once required but aren't any more aren't pushed away from poverty, but toward it.
And that's ignoring the fact people get support when they don't have work. (Yes, Centrelink sucks in many ways, but it exists)
Given the extremely low unemployment that you referenced in another comment, it doesn't look like we have issues with fewer drivers required tbh.