If you're in such a hurry that you can't even talk to a cashier at a convenience store, you're in luck -- 7-Eleven has formally launched its Mobile Checkout feature in New York City after some testing in Dallas. Locals can use the 7-Eleven app for Android or iOS to scan any product with a barcode and buy it on the spot, no store staff required -- the only extra step is scanning a QR code at a "confirmation station" to let the store know that you're not shoplifting. It's not quite as seamless as something like Apple's old grab-and-go purchasing, but it beats waiting in line to pay for a bag of potato chips.
Certain purchases still require human help, including financial services as well as anything that requires an age check (think booze, cigarettes and lottery tickets).
Mobile Checkout isn't universally available in NYC, at least not yet. It's available in "participating" stores that primarily revolve around Manhattan, although availability does extend as far north as Washington Heights. Don't be shocked if it becomes virtually ubiquitous, at least. Although 7-Eleven isn't typically known for long lineups, this could lighten the load for cashiers and improve you experience in those moments when you just want to be on your way.