Originally Posted by
ezefllying
In short, I'm not sure why Delta can so confidently declare this a mistake and unilaterally rescind it. I don't think this is an obvious, grossly unreasonable fare. Especially in a volatile travel environment from an airline that has no qualms about offering vastly dynamic pricing. It was left up for over a day, even as it was widely reported. There were no gimmicks necessary to book it. It was a published fare with corresponding fare rules.
The "why" is that the DOT allows them to do it. Although the DOT's revised policy largely came to be because of what they considered to be "bad faith" purchases of error fares that were obviously mistakes, the policy they ended up publishing has no requirement that a mistake be obvious--if pressed Delta just has to convince someone in the DOT's Enforcement Office that the fare was published as a genuine mistake rather than it being a case of seller's remorse, and based on available data it should be trivial for Delta to produce a paper trail that demonstrates it was a mistake.