Kant missed the necessity of unwritten, disavowed but necessary rules for every legal structure or set of social rules - it is only such rules that provide the "substance" on which the laws can thrive, or properly function. The exemplary case of the effectiveness of such unwritten rules is "potlatch"; the key feature that opposes potlatch to direct market exchange is thus the temporal dimension. In market exchange, the two complementary acts occur simultaneously (I pay and I get what I pay for), so that the act of exchange does not lead to any permanent social bond, but merely to a momentary exchange between atomized individuals who immediately afterwards, return to their solitude. In potlatch, on the contrary, the time elapsed between my giving a gift and the other side returning it to me creates a social link which lasts (for a time at least); we are all linked together by bonds of debt. From this standpoint, money can be defined as the means which enables us to have contacts with others without entering into proper relations with them.- Slavoj Zizek, "Living in the End Times".
This atomized society, in which we have contact with others without entering into proper relations with them, is the presupposition of liberalism.