Amazon is a combo e-retailer and e-mall. When you deal with the e-retailer Amazon, Amazon merchandises, prices, owns the goods and fulfills them from stock in their warehouses.
E-mall sellers are different -- they work the same way as Aliexpress, using Amazon's website as a store, they control product listings, some ship direct, some are sales agents and have other suppliers drop ship, and some warehouse and fulfill using Amazon. E-mall sellers set their own prices, product descriptions, shipping options and ship-to restrictions. To many customers Amazon just looks like an online store, they don't know about the back end fulfillment, pricing and merchandising.