What should they be called? The proper fare didn't load, just the taxes. There was no discount intended. Sounds like a mistake/error to me?
IIRC the issue of what to call these fares stemmed from the infamous Swiss [Airlines] mistake fares from years ago ex Rangoon, where the Canadian courts ultimately considered the issue of mistake and whether the passenger ‘knew’ or ‘ought to have known’ the fare they were buying was a mistake.
The passengers in that have all sorts of examples of other fares that were close to, or equal to the Swiss fare, and claimed they couldn’t have know this was a mistake. IIRC the examples weren’t really comparing like for like, and some were even based on other mistake fares. The court didn’t agree with the passengers.
So it was decided on the likes of FT that fares should never be called a ‘mistake’, no matter how obvious, lest a court use that as evidence that people ‘knew’ or ‘ought to have known’.
It seems however that this questions is rarely relevant. If a fare is a mistake but not obvious, the airlines have never sought to back out. They only do so where the mistake is obvious. And so it is pretty hard for most passengers to feign ignorance.
The preference is to call these ‘bargain’ fares, or something similar.
For a $300 return business class fare to Europe I think it’s a bit of a non-issue. Even in economy the closest fare on scoot would have been almost double, excluding any bags or meals. Had the initial price been listed as $300 on
Etihad maybe - just maybe - people could have thought EY was undercutting Scoot. But te full fare was actually listed initially, only to incorrectly show on the payment page.
www.dailymail.co.uk
, unlucky! 
