Quadcopter are very fast and can go very far before they lose power. And a single sandwich is not a very heavy load.
If you are outdoors and can give it your GPS coordinates, a single restaurant/quadcopter port, could serve a very large area.
e.g. sender logs a job online (& provides payment details), sender prints a barcode sticker, sender drops off package with the building doorman/concierge and/or walks to designated quadcopter landing zone adjacent building, outgoing package scanned and loaded onto quad-copter, quad-copter delivers package to recipient's landing zone, quad-copter/system sends notification to recipient to advise that package has been delivered, recipient goes to quad-copter landing zone to collect package, recipient scans barcode or provides electronic signature to acknowledge receipt.
Terms & Conditions: Anyone who implements this idea (or minor variation) must give hook and I a $1 royalty each for every job logged ;)
At this point, the FAA is _very_ serious about UAV safety, IMHO with good reason. Even with our extremely safe controls, we had one UAV crash due to launcher failure, and another get stuck up in the air a long distance away due to a sudden thunderstorm that rolled into our area.