> As the person holding the money, it's my job to look at what is effective and what the active ingredients are in any given product.

But I don't have time to do that. I would rather have a retailer do that curation for me and provide me with effective high value products, and stand behind returns when they miss the mark. Then as a customer I can reward them for that value added work.

That's why Costco is great most of the time. Although they sometimes miss the mark with certain products they stock.

Additionally, if I'm buying cold medicine there's a really good chance I have a cold, and my ability and inclination to carefully analyze the ingredient list on a box of medicine smear-printed in 3pt sans will likely be diminished.