There's a reason blocks of flats have mailboxes on the ground floor. I predict we'll see a rise of better, automated mailboxes, probably loaded from outside. After solving self-driving there is zero reason to employ a human - are companies really going to keep paying decent salary to dead weight that is occasionally useful to go up the stairs? I don't think so.

Did you just equate walking to the curb to the same level of inconvenience of having to go to the post office? I'd have to walk nearly as far to get to my car as I would to get to the curb, and then I'd have to drive to the post office, find parking, walk into the post office, wait in line, walk back to my car, drive back, carry the package into my house...

"Whelp, having to cook my own food is more inconvenient than having it made for me. At that point I might as well butcher the cow myself!"

It depends on the kind of housing and street layout. If you're in suburbia, walking to your street vs walking to your front door is a difference of 20 feet.

Also note that for many neighborhoods in the US, picking up the mail is a PITA - there's a collective mail box somewhere in the neighborhood that you need to walk to, usually a several minute walk. Door-to-door mail delivery only exists for houses that are several decades old.

If I could get a business to gather my postal mail & packages and park outside my door I would be very happy.

Post offices are much further, you have to wait in lines, not to mention finding a parking spot if you have to drive there, and most importantly, post offices usually work in the day hours. There's little reason for self-driving delivery cars can work 24/7, or at least in a much larger hour span than a post office.