One day, a blonde staying in our colony hit a biker. All blamed her for causing the accident, by making a left turn despite oncoming traffic. She angrily said, "Everybody knows I turn left here at this time every morning."
Her explanation was idiotic and definitely is metaphor for professionals. This is a unique example of 'everybody knows' syndrome. We assume that others don't need to be communicated something we know. Most of the times, we assume that other person must be knowing the said information. Even it is also assumed that the other person didn't need to know, or should have known without being told. We expect that people are superheroes and they can find out anything without being told.
Just have a look inside the organization; you will surprise to know the frequency with which this misunderstanding occurs. In large and complex organizations, the frequency of misunderstanding increase rapidly.
People assume that the others are on the same platform as they without realizing the fact. But the question is why we are victims of everybody knows syndrome? Some obvious answers might be: we're too busy to consider what others need, or too rushed. Perhaps we have a difficult relationship with others who need to share the information. Or fear of loosing something can be one of the reasons. However, we should start by looking at structures and systems rather than personalities.
In many cases the superior responsible for passing down information probably did the subordinate's job herself before being promoted. That means she probably communicated much of the explicit information to her subordinate, but not necessarily the implicit information and knowledge. Implicit information is not top of mind, nor readily articulated. It needs to be raised as an issue, digested, and put into words before it can be communicated. Therefore, it's neither quick nor easy.
The best way to ensure that the information 'everybody knows,' especially implicit information, gets communicated is to develop appropriate systems, processes that make this kind of communication systemic.
One of the major causes of communication failure is the "everybody knows" syndrome. This involves a decision not to communicate because of an assumption that everyone else knows what I know. It's especially a problem for implicit knowledge, which falls outside established systems for communication. Look for ways to ensure that information and knowledge get communicated systematically.
And, while it may be tempting to look at personalities when the 'everybody knows' syndrome strikes, you'll only get good solutions by looking at structure and systems.