"yet even within each of these in developed economies you'll find grading and quality control"
I think it's an oversight to mention bulk commodities as an exception to the need for quality information. Things are bulk commodities because there are standards and regulations that enable them to be traded easily.
"Bulk commodity" in trade means that a good is comprised of units (discrete or continuous) of equally-interchangeable quality, as opposed to a good which is comprised entirely of unique entities.
If I take a brick, or a shovelful of sand, or a barrel of rainwater, a ton of iron, a bushel of wheat, a dollar or yen or pound from you, and return another to you later, it doesn't matter if you get back the same unit or a different one, so long as the quality is equivalent.
If I take a Monet or Picasso or first-edition Gutenberg Bible or the Hope Diamond, you're going to want that specific item back, not a replica, no matter how exact or precise.
If I order a package of washing-up liquid from Amazon and that goes walkabout, Amazon can simply ship another unit of soap and I'll be happy.
If I order a pair of prescription eyeglasses and those go walkabout, Amazon cannot simply redirect another customer's order to me -- the specific nature of the glasses -- prescription, frame choice, fit, lens coatings -- matter.
Bulk commodities are highly undifferentiated. Within a commodity class, they're infinitely substitutable. Once a price is determined, what you get for that price really doesn't much matter. In other words, it's the realm of market-based exchange most amenable to price-as-the-only-signal you can find.
And yet, it still doesn't rely on price-as-the-only-signal.
Even amongst commodities, there are quality measures. You want your sand to be sand, not dirt or plastic. For specific applications, river rather than beach sand. Grain is controlled for moisture content, spoilage, and insect fragments. There are quality standards imposed by mechanisms other than price.
Your (apparent) objection to my comment was actually the point I was trying to make.
I think it's interesting to consider how consumer electronics (that is, brand name, widely distributed products) share the qualities of a bushel of wheat or barrel of oil. They aren't simple or interchangeable in that there are a vast number of unique types, but they are easily traded online because the important characteristics are all available and can be relied on. They kind of seem like they share salient characteristics with commodities. So are they commodities?
I think it's an oversight to mention bulk commodities as an exception to the need for quality information. Things are bulk commodities because there are standards and regulations that enable them to be traded easily.