If the circumstances are so dire that the worker has no other choices for employment, the alternative is no employment at all. That's the baseline comparison point for whatever job Amazon is providing and the worker always has that option as well.
Amazon is not a charity, it's a for-profit company, and arguably by building the warehouse and providing jobs it's doing more long term good than a charity would by handing out sandwiches.
Comments like yours bring to mind the phrase "No good deed goes unpunished". Would they be better off with no jobs at all?