The absence of evidence
To decide to not act is different than not deciding whether to act or not.
To know that something doesn’t exist is different than not knowing whether something exists or not.
The absence of evidence is different than the evidence of absence.
In one case, efforts have been made to reach a conclusion, even if this conclusion turns out to be a null state.
In the other case, nothing has been done or proven. No conclusion has been reached.
In business, people often confuse those two states which often leads to misunderstanding (at best), or costly mistakes.