They also offer some degree of curation, so your dollar goes further by volume/weight/unit on average, but also in less quantitative ways quite often. I trust what I buy from Costco, but I’ve completely stopped buying from Amazon (many years ago now) because apart from the poor value prop, I simply don’t like the quality or reliability of what’s offered.

I don't find Costco necessarily cheaper than anywhere else. For example, if I'm careful and search flyers, local supermarkets will often have better prices.

For me, Costco has good prices, an excellent return policy, and reliably excellent quality. I don't need 15 choices of peanut butter, just a few (smooth and chunky, natural and sugary) good ones.

I also appreciate that Costco employees are always busy, but they seem positive and friendly. Most Costcos I go to, I look for the board that highlights long-term employees. The one nearest me has 8-10 people who have been there for 30 years or longer.

As the article said, Costco pays higher hourly wages than most other people. They also provide extended health benefits (in Canada, so basic health is already covered), paid sick days, paid vacation days (one woman I talked to had been working there for 25 years and had six weeks of annual vacation!), and more.