Amazon.com Inc. is considering a plan to open as many as 3,000 new AmazonGo cashierless stores in the next few years, according to people familiar with the matter, an aggressive and costly expansion that would threaten convenience chains such as 7-Eleven Inc., quick-service sandwich shops such as Subway and Panera Bread, and mom-and-pop pizzerias and taco trucks.

Amazon Could Open 3,000 Cashierless Stores by 2021

Amazon Chief Executive Jeff Bezos sees eliminating meal-time logjams in busy cities as the best way for Amazon to reinvent the brick-and-mortar shopping experience, which still accounts for most spending. But he’s still experimenting with the best format: a convenience store that sells fresh prepared foods as well as a limited grocery selection similar to 7-Eleven franchises, or a place to simply pick up a quick bite to eat for people in a rush, similar to the U.K.-based chain Pret a Manger, one of the people said.

An Amazon spokeswoman declined to comment.

The company unveiled its first cashierless store near its headquarters in Seattle in 2016 and has since announced two additional sites in Seattle and one in Chicago. Two of the new stores offer only a limited selection of salads, sandwiches and snacks, showing that Amazon is experimenting with the concept simply as a meal-on-the-run option.

Two other stores, including the original AmazonGo, also have a small selection of groceries, making it more akin to a convenience store.

Shoppers use a smartphone app to enter the store. Once they scan their phones at a turnstile, they can grab what they want from a range of salads, sandwiches, drinks and snacks — and then walk out without stopping at a cash register. Sensors and computer-vision technology detect what shoppers take and bill them automatically, eliminating checkout lines.