There is a technical name for that in psicology: Double-bind.
There are 2 acceptable responses to that, plus a taboo one. The 2 standard responses is either to try to uphold an unrealistically high standard (the neurotic overachiever type), or you can take the blame for not doing it and sacrifice your sense of self worth (the dilbertesque, paper pusher type). Both private and public sector have plenty of uses for workers of either type.
What is not permitted is to react like a grown up and point out to the inconsistency of the "mixed messages". I have read that this typically gets responded with hostility from higher-ups (who typically are not fully conscious of the dynamics of the game, or see themselves as just transmitting the requirements from upper management).
Of course I barely have a handful of first and second hand data points, but those seem consistent with the model as explained above.