There are factors in games that mean something 'real' probably wouldn't result in a great map. Foremost is the fact the real world doesn't care whether or not there are places where a person can get stuck. A game world has be be designed in a way that means the player can't get stuck in places they can go to, and can't go in to places where they could get stuck. Depending on the game type, the map also often acts as a 'corridor' forcing the player to move through a series of locations in order. Features like that move a game map away from something real really fast.