It's to save on shipping. They got quite a bit of warehouse nowadays. They just share all the same inventory, thus have to move less stock in between warehouse

It's to save on shipping. They got quite a bit of warehouse nowadays. They just share all the same inventory, thus have to move less stock in between warehouse and you get your stuff faster. It fail when their FBA inventory is fake though, and they weirdly don't care enough about it to stop doing that. I guess the cost of refunding theses cases is less than the cost of shipping.