Amazon Go is billed as the convenience store of the future. There are no checkout lines; you can simply walk in, grab what you want, and leave. You scan in with a smartphone app, and then an AI tracks what you take from the shelves and automatically charges you for them.

A big sticking point for the expansion of Amazon Go stores, which focus on convenience-type items such as grab-and-go sandwiches, is how well the AI would handle a busy store. Now, it looks as though the technology has acquitted itself well.