The Open Courtyard in Mexican House Design
This goes back to the Spanish roots of architecture in Mexico, and beyond that to the Mediterranean culture of the classical period. The warmth of that region spawned homes that were open to the elements. A peristyle, or inner courtyard, became the central element around which the house was organized. The various rooms of a house surrounded this interior green space.
Given a limited lot size, if you are going to have a courtyard, you will need to push the walls out to the edge of the property. Thus the Mediterranean style traded green space around a home for green space inside a home. This style carried over even to smaller homes which lack an inner courtyard. The home will have a small front yard, but walled off from the street, to create an economical version of the inner courtyard.There are other factors here as well. Even in rural areas, where space was not limiting, the homes of the Mediterranean often had a bare wall showing to the outside. This was often a security feature. Remember, for much of our history the world has been a rather brutish place, and a man was not secure in his own possessions. Houses often had to act like little fortresses, especially if the owners had significant possessions.
Today the walled yards of Mexican houses offer this same defense. Burglary is unfortunately common in Mexico, and a good wall, with spikes or glass lining the top, gives a homeowner a sense of security.
This walled approach is one of the principal differences between Mexican house design and what you will find in Northern Europe and most of the United States. I qualify that last statement, because much of the Southwestern United States gets its design cues from Mexico. It has modified the Mexican style considerably, but the Mexican influence is still dominant. This is fair, since most of that region used to belong to Mexico.
When we took the land we ended up with a fair amount of the culture as well. It was sparsely populated, so it was a small influence, but it is still felt strongly in the food and architecture of the region.