Travel: Are there reasons houses are like this in Nigeria

Nigeria might be a great country with diverse cultures and opportunities but when it comes to residential buildings, difference is avoided like a disease.
All over Nigeria, it just seems that there's just one pattern to residential buildings, difference being only in the quality of the materials used and the size! They all look this way

Or this way

Or this way

Could it be that there's little exposure on the part of the construction experts to other styles of buildings and materials or is it that when it comes to taste, Nigerians are resistant to change?