E-commerce giant Amazon.com is planning to open cashierless grocery stores as it tests the use of its human worker-eliminating technology on a larger scale, Bloomberg reported, citing "a person familiar with the project."

Amazon already employs the pricey "just walk out technology," which uses of a web of software and cameras to monitor and charge shoppers, at 21 Amazon Go stores across the country. Shoppers who've checked into the store with their Amazon app simply select what they want from shelves and leave without waiting in a line to check out, rendering human workers redundant.

An Amazon spokesperson declined to comment on plans to open more cashierless supermarkets and pop-up stores. It might also license the technology to other retailers as soon as the first quarter of 2020, according to Bloomberg.

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Amazon already owns the Whole Foods Market chain, which it purchased in 2017 for $13.7 billion. It also plans to launch its own, distinct grocery store chain in the Los Angeles neighborhood of Woodland Hills in 2020. It won't use Amazon's cashierless technology in that effort, a spokesperson told CNET last week.

A 10,400 square-foot Go supermarket is being tested in Seattle's Capitol Hill neighborhood, according to Bloomberg. The first Go convenience store opened at Amazon's Seattle headquarters in 2017.

While the Amazon stores may be more efficient than traditional stores, advocates for food industry and retail workers say the company's expansion in the grocery business threatens workers' livelihoods.

It "represents a clear and present danger to working- and middle-class Americans," said Marc Perrone, president of the United Food and Commercial Workers International Union.

"Amazon has one agenda — to eliminate as many jobs as possible to enrich one multibillionaire —Jeff Bezos," added Perrone, accusing the Amazon founder of "doubling down on the cashierless business model in food retail as he seeks to eliminate millions of good American jobs."