Aldi has opened its first checkout-free store, where shoppers will be able to pick up products and leave without queuing to pay. The discount supermarket’s new site in Greenwich, south-east London, will also allow customers to buy alcohol, using facial age estimation technology to check whether they appear to be over the age of 25. The move follows in the footsteps of rivals Amazon and Tesco, who have both opened checkout-free stores. Staff will use a series of hi-tech cameras to follow customers as they do their shopping, and then bill them when they leave. Aldi had been trialling the store with employees over the past few months before launching the service on Tuesday. The aim is to end long queues in stores and could lead to more sites opening. Customers must register with Aldi’s Shop&Go app, which will allow them to enter the store, pick up their items, and …