Customers and sellers should welcome the growth of a new way to ensure that goods are delivered quickly and safely. Parcels are increasingly shipped not to home addresses but to local businesses, where they are held for pick up. This summer Amazon, an American online-retail giant, is expanding a network of delivery lockers in local shops in some of America's biggest cities as well as in London. A locker pops open when a customer enters an access code received by email or text message. Other companies are building even bigger locker networks, especially in Europe.