It would be terrible if your social contract was not signed.

Can you use the government to enforce a social contract with implied consent.

Imagine a car dealership moving into the neighborhood and because he does he requires everyone who lives within a mile of the dealership to buy a $20000 car from him.

This is a social contract.

Would anyone believe that this is a valid social contract? I would think this social contract is evil.

But you want me to believe that by staying in a county, state, country that I am giving you my consent to be taxed. So in this case we have the social contract being both good and evil at the same time. Since you cannot have a social contract that is both good and evil at the same time, you cannot use the argument that a social contract is valid.