There were perfect cities where infrastructures nicely supported the life of their citizens. Shangri-La was one of them, an ideal place. People lived in harmony a long life in what was a a perfect Smart City (and valley). Unfortunately, Shangri-La is a figment of the imagination (of James Hilton), as figment of imagination are any other ideal cities.
There are no ideal cities, there never were, there never will be.
Cities have never managed to be "smart" enough. This is not surprising. A city is a "living" system in a dynamical equilibrium. Its infrastructures can support a certain number of users and certain types of usage. As their support is good the city attracts more people increasing the number of users to the point where the infrastructures are no longer as good as they were from a user point of view. Still, they make the city work and people keep flocking as long as the city maintains a small advantage over its surrounding, although the life quality in the city degrades. This compares to the "tragedy of the Commons", expounded in the economic theory by Garret Hardin. The independent race to well being of single individuals leads to a decreased well being of them all.
The binding of economics, resources, infrastructures and service quality is such that any city has an equilibrium point that is a tradeoff between the well being of citizens and its economic sustainability. At least this has been the case for centuries. An interesting question is if a different tradeoff can be achieved thanks to the progress of technology. Empirically, we can see that today's cities are better in their capabilities to manage larger group of people (megalopolis did not exist in the past simply because infrastructures were not available to support them). However, as technology has allowed cities to increase their "capacity", problems have also got bigger and more challenging. As they say: "4-wheel drive gets you stuck in more inaccessible places".
The fundamental issue of a city being in a dynamical equilibrium state affecting/affected by economics and well being (attractiveness) of its citizenship remains. Clearly there are different equilibrium points and they basically are a consequence of the interaction between countryside and urban environment. As this interaction changes so change the attraction of the city to the point that its population may start to decrease with people moving to the countryside.
These different equilibrium points translate in different city wealth, different citizen well being (not necessarily bond rigidly one another) and lead us to consider some cities smarter than others (having a “lower” equilibrium point where lower can be measured in different ways and is more a subjective metrics than a universal one….). As a matter of fact, and a further proof of the subjectivity of the metrics and of the fundamental role played by the ecosystem encompassing the rural and urban environment, translating what makes a city smart to another does not necessarily make that city any smarter.
A new science of cities is born, the one studying cities not as "machines" but as "organisms". The approach is rooted in the mathematical theory of complexity.
I know that I am going against the flow, and declaration of many, but I feel that we will never have a Smart City.
Smart is not a destination, at least in my view. It is a long, and winding, road that has to be followed. As new needs surface (population increase, changing culture, new challenges) new solutions will have to be found and pursued. At the same time the relentless evolution of technology (we do not see an end in this century) makes new approaches and solutions available that are more effective and that make existing solutions no longer optimal. Still, the deployment of a new technology may be unsustainable (too expensive....) and that city will be stuck with what it has, although it is clear that a better infrastructure would be feasible. Hence that city is no longer as smart as it can be. And if you are not as smart as you could be, you are no longer smart.
This is typical of any historical period, it is just that in these last fifty years the pace of technology evolution is such that during the deployment of a solution you already see that a new one is or will be available pretty soon, making the one you are busy to deploy obsolete.
Hence, I feel it is important to look at the direction, at the path and be smart in pursuing it.