SmartKart - A shopping App idea - make physical shopping easier

This is about shopping in big grocery stores like Spencers, More, D-Mart etc.
Generally,

• People roam the entire 3-4-5 floors
• They will see all items/ offers.
• Will choose some and put it their cats/baskets.
• Come to counter pay the bill
• Get the goods n come out

Major Pain points for consumers:

• Need to carry the basket to all the floors
•  Carry huge weights many times
•  Stand in long q’s to pay d bill, in peak times it’s pathetic.
• Major Pain Points of retailer
•  Need of a vast space to show all the items which hard to get now a days
•  Need to put the new stock when quantity becoming low.
•  Maintain several payment counters and security checks

Idea

Idea is to completely eliminate the need to carry a cart. Completely automate shopping in a store. Below is what my plan:

•  Each User can log into their account after entering the store. Using store wifi (for better security)
•  User can just scan QR code of item they want to buy from their smart phone.
•  The item will be added to his cart and they can give the quantity.
•  At any time they can change the item list and FREEZE when they are done.
•  Even they can add their card details in the app so that payment will be automated or can do payment through online banking etc. and get out pass in mobile.
•  Retailer will take max 30mins (just a rough estimate) after list was frozen to user to pack and give his items.
•  Meanwhile consumers can enjoy gaming/entertainment available there. In my view a area of two shuttle courts is required for entertaining the customers.
• Once the packaging is done customer will get an alert in his mobile. He can simply pick and go. The pain point for retailer here is packing the items. We need think of optimizing this process. Shortly this is my idea.

Edit:

 we can have the same technology used on poster ads so that customers can sell directly from there.