Your local grocery store has store brands that compete with the name brands. Your local grocery store also charges for shelf placement.
Amazon is actually more open than other stores about this information, giving product rankings so that you could decide to knock off popular products too.
Except that overlooks Amazons intentionally messed up search function. Amazon, unlike grocery stores, doesn't really put all of the items into the same location.
On amazon, if you want to browse "electric bike tires with motors" you will have to browse through dozens of full electric bikes, electric scooters, hoverboards, tires without motors, tricycles, and all sorts of close but not quite what you're looking for items to find 1 that you might be interested in.
Want to price shop them? Good luck finding others to compare with.
It would be like looking for a 5 lb bag of white sugar in the grocery store so you go to the sugar isle and finding 1 half pound bag of brown sugar amongst all of the flour and seasonings and honey and agave nectar and sweet n low in the first 100 feet.
Any grocery store organized like that would fail and be replaced by a company with decent organizational flow.
But amazon makes money by charging the vendors on its market for visibility, in addition to listing fees, storage fees, and whatever else.
Amazon has a perverse incentive to not show you, the customer, what you are looking for when there is anything else close enough to what you are looking for that they will make more money for selling to you.
There isn't a better word than evil for this, even if it is the benign sort of evil that only added to the chaos and misery of the world without directly harming anyone.
Also, in direct response to the Gp, grocery stores buy sales data that contains their sales + their direct competitors down to the product level. It is anonymoized but freely available.
Edit: Also companies like Google scan emails for information. Amazon stopped including prices in their emails because Google was getting a direction stream of sales data with full costing info.
Amazon is actually more open than other stores about this information, giving product rankings so that you could decide to knock off popular products too.