Employees of United Dairies Ltd delivering milk and groceries in Maida Vale, London, with a pony-drawn four-wheeled cart. - 

Amazon has just announced a new service, a device really. Dash. It’s a handheld bar code reader that lets consumers speak into it, or, scan items on their own shelves -- to buy more groceries from Amazon Fresh. Selected customers will begin testing the device this week in Amazon Fresh's handful of test markets.

Sounds very high tech. But not many web retailers have managed to succeed in the low tech business of delivering bread and milk. Programming chops don't help, if what you're trying to do is pack milk and eggs.