When those reports come out that “The average Google employee makes $220k a year” or whatever, it’s totally misleading since it doesn’t account for all the outsourced labor at $10 an hour that is critical to tuning their algorithms.
As someone else pointed out, this pays substantially more than AWS Mechanical Turk. To be honest, it's difficult for me to imagine an easier job than this one. I mean, most people who would do this job could easily now make more at McDonald's or Walmart or whatever. But I think jobs at McDonald's or Walmart are considerably harder, so I don't see why this job should pay the same.
Employee is generally used as the legal definition, but if you’re only job is to work for company X under their explicit micromanaged directions you fit the colloquial definition of employee even if your paycheck is signed by a different company.