I can't say I like the grandparents "robotic" tone, but I have to disagree with you here on what all is required for coordinated efforts. People disagree locally on norms and etiquette all the time precisely because we are not robots. In fact the simple mechanism of agreeing on a price allows us to coordinate our activities despite disagreeing on so much else. Our differences play a role in making us human. So does our ability to coordinate without all being of the same mind.
On a larger scale, trade persists across legal divides - with much of this facilitated via contracts, which are actually not excluded by the grandparent comment. Here what I am really claiming that contracts are a form of generalized price. So trade, coordinated work, productive efforts large and small, are basically all facilitated by people coming to agreement on price, one way or another (unless the type of coordination involves a group of friends coordinating via friendship - or maybe some generalized version of that). The "price" agreement itself may be long winded (e.g. a contract with many conditions) but it is the basic mechanism of price that coordinates so much. Even world peace. Nations that trade together are less inclined to go to war with one another. (Absent a coercive situation that is. Without coercion, trade is mutually beneficial, by the standards of the parties willfully involved, and nobody wars with their benefactor)
Therefore, I would argue that we only need generalized prices (and a lack of coercion) in order to coordinate peaceably. We do not need to agree on norms and etiquette. Of course, if one party decides to spoil things and coerce another into a bad deal, or into conforming to its norms, etc., law becomes more important. (Of course in reality somebody always tries to spoil things so law is important from the very beginning, especially locally. I might argue that law becomes weaker anyway as we scale up towards nation state scale coordination where laws differ on both sides and contracts sort of blend into treaties). I am making broad statements about large scale action and I don't like that. Maybe better to sum up the position by saying given basic conditions - 1. property rights that try to be consistent, 2. dependable and consistent legal protection, and 3. a functioning price system (the less manipulated the better), we can coordinate imperfectly, but better than expected given the vast swaths of differences of opinion, taste, and preferences, that make us so human.