...comparable to Riverwood, and its graveyard - 'the biggest cemetery in Skyrim', where people have gone to be buried for centuries - has probably less than 20 graves.
They must pile them on-top of one another... Or there is a well somewhere... Or... life expectancy is greater than a century... thus, only 20 deaths in 20 centuries...
They must be reloading saved-games too...
Ironic that the Jarl in Whiterun identifies the city as being the biggest, and most-grand... Yet I believe Solitude has that same description. Conflicting story-lines. Mostly because both are rather small. Apparently the dozen guards all bunk together, and entire kingdoms were built by taxing all 20 citizens 800% taxes on goods that they provide for others within the same towns.
All that it would have taken, is a few more tall structures that were not able to be entered. Those make great visual blockers, and help stop over-crowding AI. But nooo.... One dozen people all huddle in the town-square, at the six shops that they never enter... Causing just enough noise and congestion and game-shudder to make them annoying, not functional within the game... adding to the unrealistic encounters.
Ok, that is unfair... there are a lot more buildings and people. But the game hides them, and expects you to find them, when they are not out and about. (It could have created and teleported a dozen or so, NPC's so they always seem to be in front of you, like GTA, or like Assassin's Creed...
Mostly, they just needed more land, faster walking, bigger actual city-space, and more structures.