I think it's sort of like first-class flying. There's no logistical reason for not boarding the plane rear-to-front, but you can get people to pay for the privilege of being first, so why not? Non-Prime customers are second priority, and expected fulfillment is adjusted accordingly.

It’s a good analogy. I must be hopelessly optimistic to think there will be a reckoning for businesses that intentionally provide a worse experience.

The reckoning would be you no longer using their business, wouldn't it?

While I still get some books from Amazon, I've been increasingly purchasing through Abebooks. They tend to be more accurate in what they stock with regards to ISBN, which is what I go by when purchasing a book as I like to get specific editions.

I doubt they go out of their way to delay the order, simply because that isn't the most cost-efficient thing for them to do. I would assume that they just have a priority queue of orders to process, and sometimes that queue gets backed up and takes a few days to clear out the non-Prime/expedited orders.