Why are you "obligated"? As you said: "Those who enter into such agreements need to realize that this is a risk, and take that into account when the agree to it." If you enter into a transaction to buy a bicycle and pay before you have the bicycle in your hands, and turns out it's an empty box, well, you're an adult, you took the risk to pay before the see the bicycle and that it's working properly yourself. That's what my dad always say. He would never pay before he has made sure he's going to get what he paid for, and making all sort of backups to make sure that people don't cheat him because he doesn't trust anyone. He gets that way because he lived in a war torn country where there was no law (i.e. government) to resort to. Fraud is to be expected, not something out of the ordinary. To his way of thinking, people are always out to get as much as they can get, as they should be, so you have to look after your own interest. Anyone who doesn't are fools. He's a pure capitalist as a result of his experiences.If I promise you a working unicycle in exchange for $30, I am obligated to give you a working unicycle if I take your money. If promise you a working unicycle in exchange for $30, but give you an empty box that claims to contain a unicycle instead, that is fraud.
And Who/what should make you fulfill your "obligation"?
Maybe you didn't read clearly, I said: "Taken to its extreme conclusion".I am not obligated to tell you that my competitor across the street is selling the exact same model for $15. That is a difference in information, and is ostensibly not fraud. I don't know why this distinction should be unclear to anyone.
"A difference in information... [that] will lead to one party having an advantage over the other" is vague and broad. You might have that distinction in your mind, but I don't read your mind, so I don't know where you want to subjectively draw the line. You have problems with fraud, but others don't, and for those, "free market principles" include allowing people to be defrauded if they are stupid enough to be taken in.
If consenting adults choose to take risks, they should be allowed to take risks. Its no one's damn business.
Tell that to the women who got AIDs from their unfaithful husbands.