At first blush it looks like progress. Next month Amazon will go public with a pilot convenience shop that has no checkout lines or cashiers.The beta model for the new "Amazon go" store is currently being tested by company employees in hometown Seattle. A corporate video explains the concept: Sensors and articifial intelligence detect what shoppers take from the shelves and add each item to a virtual cart. The price of the goods is then debited from their smartphone when they leave the store.If the "Just Walk Out" technology is implemented by Amazon for bricks & mortar retailers or is copied by them, checkout-free stores will obviously have a positive impact on their P&L.Like most employers, retailers, whatever their highly paid CEOs may say to the contrary in public, generally see their staff as a cost rather than as an asset. So they are likely to embrace the new idea with open arms. But it is surely also a tacit admission of failure.