Store brands (private label brands owned by the retailer) have been around forever and are not a Costco innovation. Every US grocery store and most big box stores sell them.
Re:Love Song to Costco
by JumpCrisscross on Monday July 11, 2022 @05:33AM
(#32053984)
The source for this article’s core claim is a pair of Reddit comments, FYI.
This article explains it better than I can: https://every.to/napkin-math/how-costco-convinces-brands-to-...
TL;DR: If you buy something like Grey Goose vodka, it's going to be the same product as the Kirkland Signature version on the shelf next to it. It is often literally from the same factory. Costco AND Grey Goose make more money by being able to sell to multiple market segments.
Read that article. It's genius and one of the many reasons I love shop at Costco.