I'm not really trying to defend Amazon Fulfillment nor do I doubt the veracity of the NPR article. However, I want to throw some anecdata into the conversation.

My ex-wife has worked for Amazon Fulfillment for almost 5 years (in Texas - not exactly known as a "worker friendly" place when it comes to having laws protecting the working class from abuse) in multiple facilities (both replenishment and fulfillment) and hasn't witnessed workers being systematically mistreated, obvious safety issues going unreported and unaddressed, etc. She makes almost twice minimum wage with medical benefits, stock, 401k matching, 1.5x + 8 hours holiday pay compensation during crunch time, etc. All of that paid to someone that has only a high-school equivalence certificate.

She used to work at Walmart and would unequivocally tell you that Amazon Fulfillment has been the better of the two companies to work for.