Tesco (in the EU) does something similar to your idea: It's called Scan & Shop, and the process is roughly the following:
1. You scan the items with your phone (or if you do not want to use it, there are scanners running the app when you enter the store)
2. Load items in your shopping cart and scan them when you put them in
3. You go to a self-checkout machine
4. The machine scans the QR code on your device and automatically loads the scanned items you scanned before while shopping (so no need to unload your cart)
5. You pay at the self-checkout machine
6. You return the scanner if you used it
Now the way they solve theft is random checks, I do not know how effective this is.
Note that the solution above does not solve the waiting in line problem, which you are proposing a solution for.
From the technical side, it is doable, but I believe you would need to work very closely with the shop.
I like your idea, but it's hard for me to imagine a company without the myriad of cameras (like Amazon) to just let you leave without anyone checking your cart and comparing it to the receipt. Especially with restricted items like alcohol requiring extra checks.
The closest to "skipping the line" solution I can imagine is having a separate gateway for customers that use your solution, where an employee only skims at your cart, thus speeding up the verification process.
1. You scan the items with your phone (or if you do not want to use it, there are scanners running the app when you enter the store)
2. Load items in your shopping cart and scan them when you put them in
3. You go to a self-checkout machine
4. The machine scans the QR code on your device and automatically loads the scanned items you scanned before while shopping (so no need to unload your cart)
5. You pay at the self-checkout machine
6. You return the scanner if you used it
Now the way they solve theft is random checks, I do not know how effective this is.
Note that the solution above does not solve the waiting in line problem, which you are proposing a solution for.
From the technical side, it is doable, but I believe you would need to work very closely with the shop.
I like your idea, but it's hard for me to imagine a company without the myriad of cameras (like Amazon) to just let you leave without anyone checking your cart and comparing it to the receipt. Especially with restricted items like alcohol requiring extra checks.
The closest to "skipping the line" solution I can imagine is having a separate gateway for customers that use your solution, where an employee only skims at your cart, thus speeding up the verification process.