[cycomanic]

This is not about making a home brand. Amazon can literally look at the sells data of e.g. some seller which sells Nike Air Jordans (as a stupid example) and go and source those themselves and offer them (the exact same brand) cheaper than the seller, because they have all the sales data. Now how would Cosco do this?

[judge2020]

Costco also looks at sales data for competing products (within Costco) and chooses to make house brands of those products.

It's not like Amazon sees sales data from someone's shopify site if people choose to sell on both brand.com and amazon.com.