Earlier quoted context omitted.
To me, the distinguishing feature of Amazon, is that it's an online "everything store" with a yearly subscription that makes delivery of most products free. Any alternatives that try to "be Amazon" in this sense, while 1. only carrying first-party listings, and 2. not commingling stock? Or, in other words: any stores that attempt to be the Amazon of ~2010, rather than the Amazon of 2022?
A lot of stores online ship free now in order to compete with Amazon. Also if you're ordering more than $25 you get free, but slightly slower shipping. I see no reason to have Prime.
In fact, for some of the things my partner orders (e.g. books from Taiwanese book shops) not only is there a shipping cost, but there are often surprise $20-$50 COD import duties on top of that cost, doubling the final cost of the order. That, for some reason, they can't just build into the order invoice. And because of the duties, the logistics provider (usually FedEx) usually refuses to actually do the last-mile delivery of the thing until they're paid; so we have to go down to their depot to pay the duties, effectively forcing us to do the last-mile part ourselves.
Also, even if a store were to offer free shipping at some price threshold (I think maybe some stores do for $100 here), I find that because most online other than Amazon aren't an "everything store", it's pretty unlikely that I'll be ordering more than a single item from them; and so I'd never qualify for the free shipping anyway. If I find a nice t-shirt, and it's $20... ain't getting free shipping from that.