Going from 2 days to 1 day has always felt more like a luxury to me – and one I am willing to pay for when needed. For 95% of the purchases I make 2 day shipping is more than quick enough.
And those of us from the Triassic period even remember the days before Amazon, where you went to a bookstore, and you hoped they had a book that you needed, and if not, oh well, we can get it in 4-6 weeks. And then Amazon popped up, and you could just order online, and it felt like a luxury to have things in a week, and then we paid for it. We didn't need those books within a week, mind. It was the Triassic, we moved slowly, and 4-6 weeks for a rare book seemed just fine. (Because, amongst other things, it gave you an excuse to spend the next 4-6 weeks browsing what other books the store had ;)
I'm fairly certain the same will happen to 1-day. It'll feel like a luxury. It'll turn out to be convenient. It'll take a year or so, and then we'll all happily pay for it.
And that's if you knew it existed. If you were looking for an esoteric subject it was not trivial to discover what books on the topic were in print.
I'm a happy non-Prime Amazon customer. I buy plenty of things from them, and I basically never need anything faster than their free shipping (which I'm pretty sure they deliberately slow down, holding back dispatching in order to incentivize customers to get Prime). I could easily afford a Prime subscription, but I don't see how it's more worth the money than a hundred other things I could drop ~£100/year on.
Are there really so few other people who feel that way?
As far as the deliberate slow down is concerned, I'm positive that they are doing that because they tell me. About half my orders from them come 1 or 2 day shipping after a 5 day delay from the time I submit the order. I get an email telling me that the item has shipped and will arrive tomorrow or the next day. Then the transaction hits my credit card. It's super annoying and I'm sure they want it that way.
Or order something at night, and have it waiting for you when you wake up.
Is this luxury ? sure.
But they also give you a certain feeling of power.people crave power.
And less uncertainty, on those 2 days of waiting. And people dislike uncertainty.
And with delivery robots on the way - the price difference between 1-day and 2-day might be pretty small.
1 day seems unnecessary sometimes, but more often it is fighting back trips to local retail for me. I.e. Terro Ant Bait with the recent change in weather in Portland.