[kelnos]

They ask you at check-in time, not reservation time, so they can't use low bids as a reason to further overbook a flight.

If a flight is oversold, it's oversold. They're going to bump the same customers with the same low thresholds whether they declare those thresholds when they check in or if they wait until they're at the gate.

Sure, there's a psychological difference between making an abstract dollar amount decision at check-in time (when most of the time no bumping will even have to occur anyway) vs. participating in a live auction at the gate (when it's actually a reality), the latter of which might result in higher payouts by airlines, but I don't think that's necessary, and makes the process much more inefficient.