> I suspect that would ruin their whole 2-day/1-day shipping bit.

They are no longer offering 1-day shipping. When I signed up for prime, one of the benefits was discounted 1-day shipping on items for which the free 2-day shipping wasn't fast enough. I recently had need of that, and learned that the options are now (1) "prime shipping", with no particular service guarantee. There is no second option. I contacted customer service multiple times asking why I couldn't choose 1-day shipping and was told "because the item is out of stock. There is only one item left in stock, that means the item is out of stock".

I've seen 1-day and even same-day shipping on a variety of items, so I suspect it's determined by some arcane combination of user location and item logistics.

They used to offer guaranteed two-day shipping and a paid upgrade to one-day shipping; now they just have "Prime Shipping" as the parent said, and what "Prime Shipping" means varies from item to item and time to time. It can mean one-day. I don't think I've ever seen same-day shipping, but I'd imagine I just don't live close enough to a fulfillment center.

They do QC: sellers that have too many complaints get kicked off.

If they wait for complaints, that's not amazon doing the QC, it's the client.

But you can’t identify which seller your product came from. That’s the whole problem here.

But when you return the defective product, Amazon can see what seller it came from.

Are you sure about that? I thought part of the whole incentive for commingled inventory was that Amazon no longer kept track of it separately per vendor and just lumped it all into the same bin without a unique serial number.

Am sure and posted the link elsewhere on this thread

Counterfeit products are still a huge problem on their platform. Great QC.

Only if they only purchased one.

Ah yes, like how if a drug company poisons enough people then the market will make them go out of business. You know, because people died.