Yes, it's a naive assumption that quality of the presented material doesn't impact consumer behavior, if they get flooded with loads of garbage books and people can't find good book they enjoy they'll stop shopping at Amazon and it doesn't matter if they make money off the slop. It's the same reason Youtube has quality filters for algorithmic feeds, if the stream gets too polluted with bad videos people will watch fewer videos.
It's exactly the same process that's causing people to avoid expensive purchases on Amazon due to the number of fake products that have infiltrated their supply. People move on if they're sold a lot of bunk goods from a place.
And yet look at all the non-book products being sold on Amazon that are all garbage. Its the same slop problem and has been for a while, but they don't seem to be addressing that either. I have to assume it doesn't impact their bottom line as much as we think it should, consumers don't (or can't) care as much as we would hope.
I don't know. For years Amazon has had a fraudulent item listing problem to the point where it's hard to trust them. They have made no effort that I have seen to solve it. I mean, why would they, their sales haven't declined.
So, I am skeptical books will be any different than all those knock-off drop-shipped items.