Earlier quoted context omitted.
That's a different problem from your previous examples, and it's the same problem whether it's ACID or not: there's always an opportunity for the user to see the item as being in stock, then request to order it, and discover it's out of stock. Your "recovery" from the case where there's nothing in stock doesn't need to happen in a transaction (and can't meaningfully do so); you just tell the user their order failed,…
I see what you mean, but with ACID you can tell the user right away if the order was successfully placed. With eventual consistency you don't know how long it'll take so you either show them a loading spinner that takes an indeterminate amount of time, or what? Not saying that the spinner solution is wrong (as it definitely scales better), but the immediate feedback is something you lose with eventual consistency, by…
So actual ACID transactional consistency requires a year. So after basic checks just say you'll give them what they want and accept payment -- since you'll need failure recovery anyway for lack of delivery, refunds, acts of God etc
So accept and plan for failure