A lot is thanks to Farouk Al-Kasim [1], who helped develop the fundamental plan for Norway's petroleum industry. As far I know, his task group's plan, developed while at the Department of Industry, was essentially accepted wholesale by the government. Part of it was ensuring the government retained control, and another part of it was ensuring oil revenue was carefully managed rather than flooding every level of society and government.
this also means there weren't entrenched oil barons (or rail barons, or shipping barons, etc.) that already had massive regulatory capture and could sway the government and economy their way.
greenfields, limited rent seeking, and knowledge of the risks -- sure enough it all went right