There is no need for the delivery to be manned. The vehicle can pull up, you enter a code and it provides the goods vending machine style. (Note Amazon already has these in several cities.)
At the moment the delivery drivers have all these work rules and health and safety regulations (eg 9-5, limited hours per day/week, holidays off etc). It makes sense to schedule deliveries around their convenience trying to get as many deliveries per driver hour possible.
But robotic drivers don't care. You can dick them around as much as you want (tell them you'll be home at 6, then tell them 7, then tell them 2am). It doesn't bug them having to wait around for you.
Consequently the vast majority of the time deliveries will happen around your availability. That is probably good enough 99% of the time. As to what happens when you are out of town, the delivery can just wait till you get back.
