Darryl Richardson was delighted when he landed a job as a “picker” at the Amazon warehouse in Bessemer, Alabama. “I thought, ‘Wow, I’m going to work for Amazon, work for the richest man around,” he said. “I thought it would be a nice facility that would treat you right.” Richardson, a sturdily built 51-year-old with a short, charcoal beard, took a job at the gargantuan warehouse after the auto parts plant where he worked for nine years closed....