They're not perfect, and I think Amazon does combine listings for the same item (see "other sellers"), but the bigger issue is that the system prioritizes getting you exactly what you ask for over warning you of weird market shenanigans or out of stock sellers meaning prices are way higher than usual.

If Target is out of the brand of paper towels I like I don't go to the next store and buy them no matter the price, I get a different brand or skip it. If I had a human shop for me, they would also get a different brand of skip it. But that logic doesn't work with Amazon so it's not safe to trust it.