My theory on how this works is as (nearly) everyone shopping on Amazon is logged in they know where you are probably going to ask to ship your order to. And so

My theory on how this works is as (nearly) everyone shopping on Amazon is logged in they know where you are probably going to ask to ship your order to. And so they show you search result tailored to what is in stock at your nearest Amazon warehouse. That way they don’t have to distribute the same stock to all warehouses. Try searching Amazon in a privet window, you get very different result and prices (from different sellers) for the same products. I think that’s down to what’s regionally distributed near you.