One other point we are not dealing with directly: where you live vs. where you travel.
Now, high level characters are primarily found in cities, but is the city environment so much more dangerous, stressful, and exciting that it brings about the XP the produces higher levels? Probably not. Many of the high level individuals may well have city "homes", but travel widely to gain the XP. This suggests that perhaps magical power might be more widely seen than simple population statistics show us.
Look at the published adventure out there -- most (just by quick glance at the FLGS stock) adventures take place out in the wilderlands far away from civilzation. The adventurers would pass through many small villages on the way to the adventure-proper. Perhaps they help out, perhaps they do not, but the people see them. Perhaps the feeling of the villagers towards the adventurers is hopeful, perhaps jealous, perhaps angry, perhaps they see a potential career move away from villages. And the amount of hard currency adventurers can dump on small villages (and would have to, for food if nothing else) could be quite staggering -- perhaps a few "entrepeneurs" in some of the more distant villages have set up "Adventurer Shoppes" to attract such individuals. That is pure speculation, however.
There is also the question of character levels, XP, and demographics. There have been some threads in the past arguing how quickly an average person raises in level with several different conclusions, but certainly common folks can, through simply living their lives, slowly rise in level. But why are there more high level Commoners in cities as opposed to villages? Again, are cities inherently more dangerous? This doesn't appear to be the case. Several of these Commoners in cities would be merchants, perhaps wandering merchants. Perhaps they get their XP while wandering from village to village with their wares. This would be fairly logical, as the road is a dangerous place.
But these wandering merchants are also interesting on an economic level -- do they only bring cheap merchandize to the villages? Or do they bring more wondrous items, hoping to sell one or two along the way (perhaps to those wandering adventurers?) and thus introduce the concept of more magic to the villages? This is pure speculation, but it is an interesting notion.
Just more food for thought
