Because the seller is still at the table.
The two windows
- Watching when you won: thirty minutes.
- It ended while you were away: twelve hours.
Two numbers because they answer two situations. How long do I have to pay.
Why the live one is short
In a live show the seller is on camera with the item in their hand and a room watching. Until you pay, that item is neither yours nor available to anybody else — and the under-bidder who would have taken it is still there, right now, for another few minutes.
Thirty minutes is roughly how long a show runs on. It is long enough to finish paying with a phone in your hand, and short enough that a seller is not holding an item for someone who has gone to dinner.
Why the other one is long
Plenty of auctions end while you are asleep or at work. Nobody expects you to sit through them, and a win you did not see is not a win you ignored.
Twelve hours covers a night. It is the difference between a system that assumes bad faith and one that assumes a life.
What the timer is not
It is not a sales tactic. Nothing gets cheaper or more expensive while it runs, and nobody can outbid you during it — you have already won.
It is a holding period with a limit on it, and the limit exists because the alternative is sellers holding stock indefinitely for people who may never return.
What happens when it runs out
The win lapses, the item is offered to the under-bidder at their own bid, and it counts as a strike against your account. Three strikes within ninety days and bidding is paused for a while.
Which is also why the under-bidder gets twelve hours to decide on a second-chance offer: they were not expecting the message either. What a second chance offer is.
If you are going to miss it
Pay first and sort out the rest afterwards. Delivery address can be edited, the parcel has not moved, and a paid order is a conversation while a lapsed one is a strike.
More: what happens when you win, how to pay, what happens if I don't pay.