There is no such thing as information symmetry between any person, or in any trade. No two people on the planet have the same information.
> which means someone will always get "screwed".
Both parties always benefit from the trade, or the trade would not have taken place. Unless someone is deliberately misrepresenting information (fraud), then nobody gets "screwed" by trade.
They are not necessarily related. Information symmetry just means that both parties know exactly the same information and neither knows more or less than the other. In a scenario where one or both parties have information that is not accessible to the other they can still engage in a trade in which each party, at least believes, it is better off given their information. A neutral/third-party observer may not come to the same conclusion but that is not relevant to this scenario.
There is no such thing as information symmetry between any person, or in any trade. No two people on the planet have the same information.
> which means someone will always get "screwed".
Both parties always benefit from the trade, or the trade would not have taken place. Unless someone is deliberately misrepresenting information (fraud), then nobody gets "screwed" by trade.