[Lockranor]

Governments are formed by single cultures with a shared value set, and a set of ethics that they believe in. Your statement that laws aren't needed until they are is accurate.

As those shared values are lost, the ethics built upon them erode, more laws are constructed. However, there comes a point where this system of check and balance can no longer function properly, and eventually, the system either becomes too unwieldy to function, or else the system is destroyed due to rebellion or anarchy.

Why? Because law is an attempt to encode ethics based on shared values. No culture which does not share values can long endure when attempting to solve the problem through increasingly complex rules with no underlying theme.