[kymaz]

The effects of costco and walmart's behavior is largely contained within their own retail space. Amazon.com has no such constraint.

I think my answer is yesno. It isn't about the action of making and selling the competing products, but about how the internet and FAANG scale changes the customer-business dynamics. Consider that when you browse wares in a physical store like Costco or Walmart, the selection is constrained to what can fit within a building, thus the absolute worthless garbage junk and knockoffs will be culled to make space for less return-prone items ( At Costco, I don't see 5 pages or aisles of identical products listed under different brands that are mechanically indistinguishable from 'kirkland signature' products). Costco also seems to care about counterfeits and whether or not something they sold was found to be bad (this has happened to me, a food item at costco was found to be the source of a few food poisoning cases and was traced back to a single item at costco, and costo went around calling everyone who had that batch on their purchase history to let them know). I've wound up with counterfeit pieces of junk off Amazon that I'm not going to go through the effort of refunding/returning/complaining about, so it's all slippage that AMZN gets away with. Returns and replacements are so fast at brick and mortar stores 5 miles away from home!