I think this is a bit off-the-mark. The point is not really a moral one from the point of view of the person getting the worse deal. Sounds illogical, but it's not: as an earlier poster said, the limit went in at 26.40, it doesn't matter to you why the market is more efficient (or whatever you want to call it), you were happy to buy at 26.39. From your point of view for that individual trade there is no case that you were scammed.
The problem is the larger perspective of the market structure being weighted in favour of certain participants. A particular class of investor is given a specific advantage by the supposedly neutral exchange, and they use it so systematically exploit an edge that doesn't exist for you or anyone else. That is wrong.
As anyone involved in bidding war with limited resources would tell you, "happy" is not a fitting word here. There is a reason why shill bidding (old-school name for what HFT does) is often prohibited or illegal.
The problem is the larger perspective of the market structure being weighted in favour of certain participants. A particular class of investor is given a specific advantage by the supposedly neutral exchange, and they use it so systematically exploit an edge that doesn't exist for you or anyone else. That is wrong.