I thought airline companies always listed cities and not nations?
Nope. Otherwise how would you know if you're booking a flight to Moscow, Russia or Moscow, Idaho?
Airline companies are not the core backbone of the digital information society.
You are correct. Airlines are the backbone of the global economy. Airlines are far more important than the internet. That's why cities build airports for free, and internet companies have to pay for their infrastructure.
I was not assessing relative importance, I was assessing relative power, jurisdiction and authority regarding the flow of information. If we want to know of which things Brussels (the city) is a capital, we look it up on Wikipedia, not on an airlines website. We might discover it is the capital of the Brussels Capital Region, of Belgium as a nation and de facto a capital of the EU institutions...