Self-driving drones that can go over curbs to deliver packages to dedicated docking boxes (equivalent of a mailbox) might make urban deliveries services faster and less costly. Each docking box could have bluetooth, an rft or mechanical imprinter to register time of delivery of package or letter and notify the recipient of arrival.
Obviously there are numerous companies such as Tesla that are positioned to provide urban deliveries quite inexpensively. Perhaps Tesla and Amazon might work together with Fedex etc. to manufacture special docking boxes and drone delivery vehicles.
Some kind of a standard box for home and office delivery drone packages should be made. As computer port standards promoted efficiency and general use there should be standard secure delivery boxes for the corporate drones to dock at, as if they were humming birds finding standard bird feeders.