While there, the photos get studied by a human eye so Amazon can also suggest related products you might want to buy. How convenient, for Amazon, anyway. The work gets sent to the company's Mechanical Turk service. There, human worker bees are enticed to do research for pennies on the hit.
Still, it's a plus for walking, breathing people -- what with Google bots and their ilk trying to take over shared intelligence on the Web. Mechanical Turk is one of a number of Web researchers, including ChaCha, that link research needs to far-flung humans.