I'm betting the Chinese tool and die makers work for a fraction of that. Which would be the real reason Apple is manufacturing in China, not some mythological self-serving crap about how no such people exist in the US.
Its probably also a bit harder to make them work 85 hours a week, stay in overcrowded dormitories and exploit underage workers. Not that that continued to happen in the years following the 2010 reports and is likely still happening today or anything...
Also - number of workers in an area tends to have some correlation to employers offering jobs. If Apple really cared they could easily start a job training program or slowly increase the number of US tool and die positions they are hiring for