[toki5]

The legal answer to your question is that they reserve the right to refund your ticket at any time up to the point of you actually being in the air. Buying a product at a retailer, where your interaction ends when they hand you a receipt, isn't really the same. The comparison would be better if United had tried to charge consumers after the flight. The real question, if you want to use the Rite-Aid example, is "should the employee be allowed to investigate the $1 price tag upon seeing it rung up," and yes, in my opinion, they absolutely should.

That gets to the moral answer, which I think is what you're really asking, I honestly don't think it's that black and white. From the perspective of a business, there are two phases to this mistake, right? The first is letting them buy a ticket; the second is honoring that ticket. The first part doesn't hurt; the second hurts a lot. If I can catch that mistake before the second phase, why shouldn't I? Maybe I'll lose some customers who are genuinely upset that they couldn't take advantage of a bug in my software, but in the long run, I'm not convinced it's harmful.

Meanwhile, from a consumer standpoint, as someone who has -- many times -- bought things at a premium discount because of a bug in software (preorder costs for video games are especially vulnerable to this), each and every time I make that purchase, I'm willing to accept that if they catch it before they ship it and want to refund me the discounted purchase price, fine. I know I'm exploiting someone's mistake and I feel like that's not completely honest.