Inside Amazonís robot-run supermarket that needs just 3 human workers

With the bare-bones payroll, the boost to profits could be huge. Indeed, the prototype being discussed calls for operating profit margins north of 20 percent. That compares with an industry average of just 1.7 percent, according to the Food Marketing Institute.

Labor accounts for the lionís share of a supermarketís operating costs. In 2015, the industry employed 3.4 million workers nationwide, with an average grocery store employing 89 workers to generate annual sales of more than $2 million, according to the trade group.

Amazonís prototype, meanwhile, doesnít call for any cashiers. It might, however, employ ďgreetersĒ that could serve as curbs against shoplifting ó a key hazard for thinly staffed stores ó in addition to using high-tech motion sensors to track wayward goods.