For the last few years, Amazon has been experimenting with what they called just walk out technology. Their Amazon Fresh and Amazon Go stores had no cashiers or cash registers; your app tracked what you bought. Amazon hoped to sell the technology to other companies but wanted to iron out the problems in their few retail locations first. They pulled the plug on this experiment this week because it didn’t work. The computers never picked up everything, so humans had to oversee the process, and that defeats the point…