ok. So every item is packaged to the degree necessary so the machine can pick it, transport it and put it away.
This isn't a far fetched idea either. Walk through a Costco (local availability may vary) and look at how their items are packaged. They dictate packaging to their vendors for most items. Even fiddly things like pens and razors are packaged in a common form factor. Everything else is in boxes.
That may get onerous for some vendors and items, but it could work for many.