Consent is a very important feature of ethical analysis.
Imagine the hypothetical, where Bob makes an agreement with Jill, that she will have sex with Bob, and in exchange, Bob will pay Jill an agreed upon sum. So far, while some persons may question the morality of such an arrangement, I hope we can agreed, that nothing strictly unethical has yet occurred in our hypothetical.
Now imagine Bob and Jill are in the act of completing their agreed upon arrangement {don't think too hard on it, you'll go blind ;-) }, so long as they both maintain their consent for the arrangement, nothing unethical has occurred.
Yet, imagine that either party, either Bob or Jill, while in the act of coitus, expresses to the other, that they withdraw their consent from the arrangement; what then? If either party, does not respect the other party's wishes to withdraw consent, I believe both you and I would be in agreement that the act which would then take place, could only be described as rape.
The feature of voluntary consent then, is critical to the ethical analysis and the mere expression of the withdrawal of that consent, is an act sufficient to make any previous contract or agreement nugatory.
In our hypothetical of Bob and Jill, if either party were to withdraw consent, the other party must cease and desist further non-consensual action and then the parties must re-negotiate the terms (if Bob withdraws consent after services having been only partially rendered, how much does he owe Jill and vice versa), yet neither party would be fully in their rights to enforce the full completion of the agreement, in the spite of non-consent.
Under this reasoning, no amount of presumed consent, would be sufficient to continue an act, contrary to the wishes of one of the parties involved.
Therefore, any argument that resorts to presume a person's consent to a past agreement, due to the geographical position that they reside, could *not* maintain itself in the face of the withdraw of consent by any individual party.
Therefore, just because Jane, lives in such-and-such a place, no person, or group of persons could ever ethically enforce a supposed contract against Jane, in the event that Jane withdraws her consent from the supposed contract.
If ever a "social-contract" or "Constitution" existed which was consented to by all parties involved explicitly and unanimously, it would become null and void to any individual which withdrew her consent.