"Learning new skills can help, a little. At Ingram Micro, temps trained to drive forklifts earn $10 an hour. " That's pretty much the way life works...anywhere. The more you know, the more you're worth.
I think the point of that quote was to show you how little even skilled warehouse workers can expect to make. The more I read about the proliferation of temps in the US the more depressed I become. I know someone who works as a "permanent temp." There is no end date to her assignment, and she works 40 hour weeks year-round, but she will never be hired as the company (an Ivy League university) doesn't want to be responsible for her benefits. She has a Master's degree and does highly skilled work for them, I can't imagine how tough it is for temps on the other end of the educational scale. It's an entire ecosystem of "disposable" workers.
Pretty sure this is the warehouse the author was working at.