how are brandings such as Kirkland Signature(Costco), Simple Truth(Kroger) or 365(Wholefoods) any more obvious than what Amazon is doing with "our brands"?
The comparable to Signature/Truth/365 would be Amazon Basics. The branding is consistent and minimal.
As the article points out, Amazon has dozens of other house brands that are not associated with Amazon. Amazon's argument would be that they are perfect substitutes, so branding them consistently with Amazon Basics would make people think they are lesser quality. So they just give them a new house brand.
Target is doing the same thing by the way [1] but they just don't have the massive scale.
[1] https://corporate.target.com/article/tag/385/owned-brands
You can buy simple truth milk, chicken, soup, and diapers at Kroger stores.
Amazon has multiple distinct brands per category, which makes keeping track much harder.
Many of those brands are not obviously private label. Whole Foods and Costco are the exception in that they have only 1 store brand that everything is labeled under. This is probably because they are high-value brands unto themselves and it's advantageous to put their own stamp on it.
some cross boundaries as I have found Kirkland brands outside of Costco.
if anything Amazon at least is up front about it.
The biggest clue is usually that it is the only brand that isn't a big name, and yet, there is plenty of it. On Amazon, there is a huge variety of lesser known brands, so you can't assume that just because you didn't hear about it, it must be the store brand.
The pricing is another clue. Store brands usually have a well defined spot, with no competition in that spot. Typically between the no-name stuff and the name brand. Amazon has a lot of brands in every price range.
I am of course assuming that it is not obvious. If a brand bear the name of the shop, or is used for every product category in the shop, it is obvious.