So explain to me why anyone would intentionally get into this business?
Come to the UK and you will see that most of the major supermarkets offer this service.
A company called Ocado have been doing this since 2002 and dont have any physical stores, everything is picked from a central warehouse.
Tesco's largest stores will have around 4 or 5 vans that will deliver your order meaning your order wont come from a central warehouse but from a store that is closest to you. They even have a iPhone app that lets you scan the barcodes of the products you use to add to your basket.
Who is your target audience?
Everyone who shops for groceries who might want them delivered.