I completely understand the esthetic reasons for zoning neighborhoods to be consistent looking, but not even a house of bomb shelter quality on five acres than no one else can see is possible in many jurisdictions.
Often, the building codes in my country specify construction materials based on the assumption that the house will be above ground. So, the house part itself must be built of certain materials. An underground house is essentially a really nicely done basement -- in their terms. It would "take jobs away" or at least contractor income.