I've spent a lot of time in my career extracting info from the business and I think most do understand the whys/why nots but aren't practiced at organizing all of those decades of experience into a higher level abstract model that can easily be communicated.
It's typically layers and layers of information with dependencies in many directions littered with exceptions. Just like our software design+dev experience, it takes a lot of practice to try to organize all of that info into a coherent presentable model.
They will do that on examples tho. They will recognize and explain every single exception they see - but they are not able to list all exceptions up front. Because, that is highly unusual task