Cars are core to American culture in the sense that Americans view cars as an extension of themselves and even their physical bodies. Traversal by foot is literally impossible in this nation so this moving steel bubble is the only means of the average American to assert his freedom socially. Because Americans are fiercely independent they see every car on the road as a competitor, someone literally and figuratively trying to beat them to the punch. Zipper merging practically does not exist here because the idea of someone else "getting ahead" is unthinkable. There is no driving ettiquette just as there is no shared social contract, everyone in public is a hostile stranger keeping you from time, status, and money and if you aren't winning you are losing.