The workers are paid what the market is willing to pay them. If there is an inefficiency/mispricing and someone can get better compensation elsewhere (for the s

The workers are paid what the market is willing to pay them. If there is an inefficiency/mispricing and someone can get better compensation elsewhere (for the same skill set, presumably), then it makes sense for them to arbitrage that gap and change employers. If enough people leave Amazon, then Amazon will have to start paying people better, and ultimately, the gap will close.