Also it is strange to me that a pizza is delivered 100% of the time yet a package success rate is much less - they seem to have the last-mile problem solved. Maybe all HDNL and the like need to do is pick up the damn phone when they can't deliver!
I'm an example of an outlier; I live in a rural area and if I go to Domino's website, there is no delivery to my house. However, I know that if I call the local Domino's that's 10 miles away, they will deliver. Problem is that there is a high rate of phone calls from drivers that say "I'm lost," "Your house isn't where they said it was," "Are you sure you live on xxx st? I drove from one end to the other and the address doesn't exist." I've learned to keep my phone near me if I order pizza because I'm likely to have to give the driver explicit instructions on how to get here.
OTOH, USPS, FedEx and UPS have absolutely no problem finding my house.
That means the company has lots of individual restaurants with their own delivery operations (guys on bikes) who handle that last mile on an individual basis, or maybe doing a couple of pizzas at a time.
If you've ordered a pizza, then you're also pretty much guaranteed to be at home. There's not much point leaving a note saying your pizza was taken back to the depot or left with your neighbour!