Did you spot something odd in the picture? That shows a map of plane routes in a calendar year over some of the most populated areas of Asia. While the yellow spots thoroughly fill the areas like Pakistan, India, Russia and Eastern China, there is virtually no traffic over Tibet! Don’t fret over why this would happen because we have a valid explanation for this:
You can testify this fact by visiting a library with a 3D globe, take a thread or a string to see how many major destinations fall directly through the Tibet region. Shockingly, these are very few. In fact, Heathrow airport, which is one of the largest in the world, only has four routes that fly over Tibet.
Another major reason for the lack of direct flights is the fact that the polar routes from North America to Asia do not fly direct to India, as it is beyond the range of most aircraft. Moreover, Europe to Southeast Asian travel is routed via Dubai because it is cheaper than going through Tibet. Thus, preference for cost-effectiveness also counts for one of the reasons for absence of yellow spots over Tibet.