Felix Salmon discusses cases where people order expensive bottles of wine by mistake and receive an unexpected bill for thousands of dollars. He is strangely unsympathetic ("... you have no one to blame but yourself ...") considering his position when people accidentally trigger exorbitant bank fees. In my view it is the restaurant's responsibility to make sure people know the price when it is out of line with the rest of the meal. Especially since expensive wine is basically a scam (people can't distinguish expensive wines in blind taste tests).
I don't actually know the legalities if someone refuses to pay (based on a sincere misunderstanding). There was no contract because there was no meeting of minds (mutual agreement on terms). I don't know what courts do in such cases, where the transaction can't be unwound, perhaps try for an equitable resolution of some sort.