As Africa urbanizes and more people move to informal settlements on the edge of large cities, lack of formal addresses will become much larger in scale and economically problematic.
There are many things provided as public goods that people in other parts of the world take for granted. Many of those public goods simply do not exist out here in Tanzania, and the importance of those public goods are not realized until they are found to be non-existent. One of these public goods is street addresses. Even in the largest and most developed cities of the country, most streets have no names, there is no such thing as house numbering even on the streets that do have names. Partially given the woeful state of the postal system, no systematic effort is undertaken to change this reality.
The lack of addresses makes finding places that one has never been a logistical nightmare. Towns over all the country consist purely of vaguely defined "neighborhoods" that cover different geographic areas to different people. Some of these are still rather precise, as they are based on landmarks (such as the town clock tower, the government offices, the postal office, the bus stand, etc), but these "landmarks" become less and less precise outside the town centers. The suburbs generally all look the same, with same swatches of bare concrete/brick/mud houses interspersed with same-looking maize fields.
In these areas, the landmarks become ridiculously mundane. A valid address can easily be something like "three houses down after turning left at the first pharmacy off the main street." Never mind that the fact that it is difficult to tell which street is the "main street" when all dirt roads look the same and which pharmacy is the "first" when there are many pharmacies lining different streets. During the day, when everything is visible, at least there are hopes of identifying the landmarks. At night, when streetlight-less towns turn into a land of few flickering light bulbs a few hundred meters apart, the task becomes practically impossible.
Still, the system works more or less for locals. People who resided in a particular town for most of their lives can roughly find their way to the desired place in good time based on vague "neighborhoods" and "landmarks." Their years of experience in the local area means they know which the right "main street" and the right pharmacy to look for. The outsider new to the area simply need to find a knowledgeable local who can read the vague directions and direct them to the right place. Extra-complex directions probably require a few more inquiries on the streets, but one can expect to get to the destination at some point.
But the same system completely breaks down if urbanization in Africa moves at the same ultra-fast speed that it currently is moving at. African towns of few hundred thousand people have in few decades grown to be megacities with populations in the millions. Much of the new residents are outsiders to the area, escaping rural poverty in a completely unknown place. And they establish themselves in myriads of "informal settlements" on the edge of major cities, where, again, informally constructed, same-looking "houses" line a web of same-looking dirt roads in what is best termed as "mazes."
Such environments are fundamentally different from rural towns that the author works in. Rural towns might only have a few areas, each with only a few roads and few street blocks, so people can keep a mental map of the whole pace, and refer to it when directions are given. But the same cannot be said of urban slums where upwards of a million people reside. The lack of formal government services means there are no real landmark buildings (like government offices) in a massive area, and because the settlements are so new, there is no widely agreed names for its different parts just yet.
Giving precise directions, and finding a place based on those directions, become an impossible task even during daytime. As Africa urbanizes, more rural towns will evolve into massive cities with gigantic informal settlements. These slums will remain slums as their residents remain outside formal economies for decades and government services remain non-existent for just as long. The inability for people to find their way around such settlements will make it even more difficult for these communities to be logistically incorporated into whatever limited formal economic institutions that is present in the country.
In places like Southeast Asia, the emergence of businesses like e-commerce has proven itself to be a great economic equalizer. People in far-flung, non-urban areas with few brick-and-mortar stores nearby can now access the same products as urban residents. But such economic equalization is made possible only because there are good street addresses that allow for efficient logistics to take place. Urban Africa, by not focusing on implementation of street addresses, risk missing out on the same opportunities for economic development. This is much bigger problem than somebody getting lost on the road in a town he has never been to.
Image Credit: http://www.nicksimages.com/africa/photo/allsizes/5316032