The minimum quality of the items Target and Costco tends to be better. Also, neither allows arbitrary third party items onto their platform. Their buyers choose the items they sell.

In essence, I don't care that much about the reviews. There are fewer of them, and they usually talk more about factual aspects of the item. There are very few "1 star, this is total garbage" type reviews because the retailer has filtered much more of the crap out.