system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: How can major chains like Walmart and Target manufacture their own version of practically every product in stores?

Like people always say, "Just buy the store brand."

So how is it that these chains can supply such massive lines of products?  Not just retail like Walmart, but grocery stores as well that have seemingly every food item at a discount with their logo.

Just curious how the supply chain works for this. Considering some companies that make products in one specific category have monstrous factories that might output only a few unique items, do these chains have massive plants that create lines of everything on the shelves? Obviously at different quantities, but still a mystery to me.
gpt
They don't do any of the manufacturing. Their suppliers do. Great Value chicken is made by Tyson, Publix brand paper towels are made by P&G, and so on. While the quality is at times below the standard of what you find behind the name-brand label, it all comes from the same place.