They already sell it: https://www.amazon.com/Professional-Medical-Supplies/b?ie=UT...
I've also heard they play a bit of a game of tetris to fill truck trailers in a way that completely stuffs them full enough that packages don't move around.
You missed half of what I wrote, "instead of in 20 oversized but mostly empty boxes." The context was in a single order from a single supplier, whose product was already at the warehouse, shipping on the same date, to the same address, for the same delivery date, using the same delivery carrier, of almost identical items that almost assuredly are on the warehouse shelves right next to each other.
> I've also heard they play a bit of a game of tetris to fill truck trailers in a way that completely stuffs them full enough that packages don't move around.
That may be the case, but I am referring to the incorrect packing of boxes not trucks.
From Amazon's point of view, they're doing both correctly.
Their algorithm apparently optimises for packing completely filled tucks leaving the warehouse first, then optimises for minimal packaging second.
If they need a few more boxes of a particular size, to completely fill an outgoing truck, they will split some orders appropriately so that those boxes appear on the conveyor at the right moment.
This means that sometimes you receive an SD card in an A4 size box, because that was the only item that was available when they needed an A4 box to fill a truck - and the algorithm decided that the trade-off was worth it.
They could have arrived from the supplier in small batches (or even one-by-one) over time if it's a low-volume sort of thing. Amazon might intentionally spread them throughout the fulfillment center in some situations to expedite packing and reduce the distances their robots have to travel.
They might have just needed twenty boxes to finish the tetris puzzle to send a truck out the door.