This whole question brings me back to the apocryphal tale of the famous bank robber Willie Sutton. The story (which has been exposed as myth) goes: when asked why he robbed banks, the bank robber Willie Sutton replied, "because that's where the money is". A perfectly good explanation, in his view, but certainly not the sort of explanation the questioner was looking for.
The moral of this story for our purposes is that general explanation seeking questions (why questions) are ambiguous - legitimate answers to these types of questions can vary according to the explanatory context applied.
What stands out for me is context. When asking questions or assigning work, the context of the task is incredibly important. I've seen this when building project plans. There is a basic understanding of the goals of the project, but the specific tasks and logic network will always be subject to review by the team, who aren't going to fully understand what the planner was thinking. Understanding that context up front is so important: does everyone share the same context? Can they be made to at least see each other's world views?