Fine, don't call it a social contract. Call it a foo. People, collectively wielding more power than any individual, agreed on a set of rules that make collective life better (in the view of those people). These rules are the foo. If you are in the geography where these people, your fellow citizens, have power then you must follow the foo or face consequences. If you don't like the foo, you can leave.
> I'd like to see the social contract be an actual contract that you opt-into
How would you propose enforcing laws? The U.S. Constitution and its ensuing legal corpus is the law of the land. If you don't like it, you can "opt out" by leaving.