DeletedUser25273
What is "Fair" can be different that what you are willing to take. If you are desperate, you will often take something that you consider unfair because you really need to. The concept of "Fair" is a bit different that acceptable.
Maybe in the theoretical 'Ideal' market, exchanges would all be 'fair', but no market is really the 'Ideal'. One of the biggest factors is an Ideal market assumes informed and rational actors, and we know how unreal that assumption would be. If the interface indicated that a trade was outside the 'normal' bounds for such a trade, I suspect that there would be a lot less people trying to cheat others with 'unfair' trades.
Maybe in the theoretical 'Ideal' market, exchanges would all be 'fair', but no market is really the 'Ideal'. One of the biggest factors is an Ideal market assumes informed and rational actors, and we know how unreal that assumption would be. If the interface indicated that a trade was outside the 'normal' bounds for such a trade, I suspect that there would be a lot less people trying to cheat others with 'unfair' trades.