This is my understanding: some brands pay amazon extra to avoid this happening but the default is that anyone can send in anything for sale on amazon.
So, let’s say Makita makes a particular drill. They obviously stock amazons warehouses with a shipment of it so it can be prime eligible etc.
Now someone else manages to buy some of these same drills for cheap at a store closing sale or whatever. They also send them to amazon for sale because it would be a tidy profit without much hassle.
And now me, a shady “businessman” who gets a bunch of counterfeit/defective/somehow subpar few pieces of the same drill. I also send them to amazon because they cost me 10$ a pop to make but sell for 200$ on amazon.
All these all get put in the same bin in the warehouse because they all have the same barcode on the box. As far as amazon is concerned, a makita xyz drill is a makita xyz drill is a makita xyz drill.
And when someone purchases one, an overworked warehouse employee comes to the bin, picks any one drill, and sends it to the lucky customer. They might be getting the real deal that was shipped from makita direct, the might be getting one clearance stock seller's or they might be getting the one I sent in. Nobody knows because afaik amazon doesn’t even track which particular item was sent by whom.
Instead, they use a random algorithm to choose which seller “sold” this drill and gets the money.
The beauty of it all is that I might get the sale (and the money) but using a genuine drill from the other two guys. And then one of the other two get the sale but one of my drills ship.
Amazon dgaf because they either made their commission or they charged the seller for shipping the thing and then handling the return. The customer shrugs because they get a refund and maybe order again or they price match elsewhere.
It’s a scammers wet dream and there is no accountability whatsoever. Co-mingling is a scourge, honest sellers hate it, yet it continues unabated because it’s a goldmine for amazon.
This happened so many times to me on amazon Canada I stopped buying there altogether. This and the classic obviously used and returned item sold as new (best one was a pair of Wahl clippers with someone else’s hair in them)
Hopefully that explains how the whole scam works.
Now amazon gives the option for sellers to pay amazon extra and avoid mixing stock. Which means if makita buys this service then only the items shipped directly by makita to amazon will be sold under their listing. And then you’ll have another listing for the same item at a different price which will sell whatever everyone else sends in to amazon as a Makita xyz drill. You, as the ~~mark~~ customer have no way to tell if it comes from commingled inventory or not.