Human beings are unevenly distributed about the globe. In a few places we will find millions of people living within a few square miles. Elsewhere we have zero population. Thus the distribution of human beings ranges from impacted, to dense, to settled, to sparse, to zip. The same disequilibrium of human abilities is evident.
Some persons can perform in a superior fashion at almost any endeavor or enterprise.
Some have very meager competency. Most of us occupy the undistinguished center, capable or even superior at some tasks, bumblers or worse at others. And there are a few, always, who cannot manage. Were I to attempt a teaching of economics, I would try to make the foregoing points clear. Much more could be said in every instance, of course.