"All contracts are fiction. Even if the telepathy issue could be solved. They are photographs of mental states which are not lasting. They are as valid as showing an alcohol test you made one year ago to argue you are not driving drunk today."

True.

But there are clear benefits to society of allowing the fiction of holding your future self made to promises made by your past self.

Though I do like the possibilities to try to break the contract;
"Your honor, I signed that over seven years ago. Every atom of the party agreeing to the terms have been replaced. So I see no reason why "I" should be held to what that other bundle of atoms agreed to do.

Further, due to atomic cycling, the other party in the contract technically no longer exists."

"Why is it that when X and Y contract and then X backs off, then if the contract involved sex, Y is guilty of rape,"

The difference between sex and the "performances" covered by fraud are because of both creativity, interactivity and the understanding that a sexual encounter is an ongoing thing. Additionally, the "seduction process" often means that what was initially contracted was a "french kiss" and everything else developed later.

Usually the terms of other "performances" are spelled out clearly. And the request for new services or conditions requires a new or updated contract with the opportunity to sign.

"Sure, you were hired as a fry-cook. But when the windows were damaged by hail you didn't become a glazier to fix them. I'm firing you for failing to perform another person's job when you were asked to do so."

And imagine a sexual encounter with a "union-rep" present;
"Hold on there Ms. Fredrikson, you contracted to jack him off. Use of the tongue was never mentioned. Is Mr. Fletcher willing to buy another drink in exchange for the introduction of oral?"

Though, the newly discussed "Yes means Yes," laws will turn sex into a combo of contract negotiations and play by play.

And I suppose they will be an end to oral sex since its very hard to assent to a change of position with your tongue buried in someone else's moist bits.

Dante