Maybe you're right, but this is self-serving and not serving the goal of presenting the cheapest products to customers. There are so many low-quality products on Amazon. Often the packaging is outrageously wasteful as well. For a bottle of supplements, they often sent a box within a box, filled with so much plastic, paper, etc. The environmental impact on Amazon is huge!

Actually, I would make the case that this is best for customers. Amazon would be better served by optimizing for revenue (so higher prices would rank better), but customers are best served by what other customers like/bought (so number of orders would rank better). Also, products have plenty of opportunity to surface in search results. We have some top ranked items and Amazon constantly rotates products through all parts of the search results. Probably the reason that you're seeing lower cost items ranked lower is that they're not very good products. The listing copy and images are probably bad, so the listing doesn't convert. Or there are lots of returns. Stuff like that.

Not really. When I'm looking to buy product A at the lowest possible price, I don't care what somebody with totally irrelevant to my needs have purchased. Also, the quality of product names and description with Amazon is below any decent standards! They shut down my Amazon Pay account as I had an out of stock item, which didn't have Nutrition Facts. But, tell me, how many of Amazon products have those labels? Most of blury pictures, often outdated, etc. If only they apply the same standards to their stuff!

This is good insight. I have done some searches recently and found products that are at the best price seem to be buried. Maybe it's because they are bad products.