Oh, nowadays are local ordinances passed by unanimous consent of those to whom it applies?
That's the difference. I can agree to have someone command me when and when not to breathe by joining an orchestra, but such a restriction can only be made with my personal consent. It cannot be made by a vote or a caucus or a bureaucracy or a representative body or a referendum or any other delusional process -- I, personally, must agree to limit myself in this way.
Under libertarianism, I may buy up 50 square miles of land and form a city on my land wherein the rule is that everyone must walk on their hands at all times. Or have no free speech, or be disarmed, or not use drugs, or not eat dog meat, or not torture dogs which they own. But I can only make those rules for land which I own.
"Contract" and "ordinance" are miles apart, across an infinitely huge chasm. And that chasm's name? Consent.