Is the Army and it's orders, MOS assignments, leadership requirements and all other things Army really hard to understand and figure out ?

The Army has ten times more people and they don't want to make it too easy.

No, it is not that hard to figure out. Now getting it to work, is a different question.

The issue isn't whether it's easy to understand (because it IS easy and straightforward for the most part). It's whether or not the process was ever explained in the first place.

But as LTC Shaw stated, the Army is much bigger than the Corps is, and much more diverse. That alone lends to a level of complexity that the Corps doesn't have to deal with.