"How does the package get from the self driving car to your porch?"
The truck never stops, optimizing its route for all the drones it has in the air.
Writing that code would be a pretty cool job.
But that's the problem: no matter how many variations of the obvious you list, they'll find something to patent.
Even after you account for a minimum price to make it worthwhile, that's many, many more deliveries than UPS/FedEx does.