"The scandal is that it would take so little effort on the part of Amazon to significantly improve the working experience."
I have observed bait n switch as a labor force management technique... lure in "good" workers by promising awful pay and benefits not, but 4 years in its pretty awesome. Then make actual conditions, procedures, and policies such that everyone is fired or quits by 6 months in.
Used to see this a lot for health insurance. Nobody gets insurance for first 90 days, coincidentally everyone is fired for cause or quits in disgust less than two months in.
A business can save a lot of money that way. Not saying its right, just explaining why a business would intentionally boost their turnover rate or refuse to make the simplest change to lower their turnover rate. Its not a bug, its a performance eval oriented bonus rewarded feature.