It's hard for me to say Amazon shouldn't be able to do it while every grocery store can, but there seems to be a quantitative difference because of the ridiculous number of options online vs the finite shelf space of a brick and mortar.
All the same economic games are played. Items are placed on specific shelves to drive specific sales, etc. Sale numbers are known by the store and they get their cut.
The distinguisher is supposed to be in the quality. Premium vs generic. That doesn't seem to play out healthily in Amazon's marketplace.
Maybe one difference is the consumable nature of the grocery products vs what one typically buys online (Amazon batteries as opposed to an animal carrier). Or maybe we have given up too much with the consolidation of grocery chains the last few decades and that is equally problematic.
I’m all in favor of suppliers competing with each other, as that’s in the best interests of society overall. But when the platforms/marketplaces themselves participate in that competition they have tremendous advantages, which is anti-competitive, and it benefits no one but themselves.
The FBA middlemen are more like traveling salesmen - they take an order, send it in to HQ, and HQ ships it to the 7-11. They don’t do anything but take orders. They are Tom Smykowski - they take the plans to the engineers!
You’re complaining that the storefront that the goods are sold through has its own sales information. The amount of sales you have through Amazon may be a trade secret, but it is not a trade secret from Amazon.