Maybe you should have read OP's comment until the end before posting your angry reply. He said, that if laws were perfectly enforced, it would basically mean that the set of laws would very quickly be trimmed down to the set of useful laws. In the examples you cite, pot would become legal, and we would get better traffic laws (i.e. "contextual" speeding laws, only when children are present on the pavement/only when the visibility is low).