[Closi]

> Just because they purchase and resell inventory doesn't mean Costco (or Walmart or Sams Club etc) doesn't hold the same power over their product suppliers that Amazon does

With the Costco example, Costco as a retailer holds power over their product suppliers. If they are making an own brand, what they are doing is buying it from another supplier and asking that manufacturer to put their own label on it. These relationships can be anti-competitive and present opportunities for market-abuse, but in a meaningfully different way to the Amazon example.

With the Amazon example, Amazon holds power over other retailers using their platform.

And with the Walmart example you have stated, I do think that suffers from the same problems.