Bezos upbeat on Amazon Go physical stores

Bezos said the implementation was complex, with specially designed cameras and shelves and new computer vision algorithms.

In his annual letter to shareholders, Amazon chief executive Jeff Bezos was upbeat about the prospects for Amazon Go, the stores where customers use an app to check out, with purchases scanned in the store and billed electronically to eliminate the need for cashiers.

"For many years, we considered how we might serve customers in physical stores, but felt we needed first to invent something that would really delight customers in that environment," he wrote.