Well, if different courts were allowed to exist in the same geographical area, with different laws, selling their services (and their laws) to customers, compet

Well, if different courts were allowed to exist in the same geographical area, with different laws, selling their services (and their laws) to customers, competing for these customers, and negotiating between themselves as to how inter-court disputes should be resolved ... then different cultures living in the same places could live by the laws that best suited them, with maximally-efficient interaction with other cultures/courts, without people having to geographically segregate themselves into multiple homogeneous nations (such a transition being inefficient and outright disgusting). But that won't happen, because everyone's minds are married to the idea that law must be provided by a monopoly called "government".