Amazon express stores have your card on file. You scan the app to enter then take what you want and leave. There is no checkout process.

Through automated tracking it detects what’s you’ve picked up and bills you after you walk out.

Stores have few to no employees most of the time.

'Amazon Fresh' in the UK have no scanning. They use cameras and AI to see what you pick up and you just walk out. You still have to scan your app when you walk in - face recognition would complete the experience.