Your ideas are very interesting. What you miss is that with rare exception law is a result of negotiation and not a result that can be imposed. At least in States that have representative government this is true. For a law to be effective there must be consent among the governed.

In a sense laws are tested in various cities and states before being imposed nationally in large countries.

Certainly lawmakers should attempt to understand the effect of a law before passing it. People often react to a law altogether differently than the proponents expected. Since people are not lab rats there are real limits on ways to test regulations and laws.