Initial endowment
Popular wisdom notwithstanding, there seem to be important cases which do not readily fit standard explanations for why New Public Management developed in the 1980s. Another possible explanation is the baseline, or initial endowment from which different administrative systems start.
Specificially it could be argued that for an administrative system to move signficiantly towards New Public Management, it must be set up at the outset in such a way as to provide both motive and opportunity (conventional elements of detective fiction) for incumbent politicians to want to shift the administrative system sharply in that direction.