The flaw isn't that it is not realistic enough, but that it goes too much against an average human's preconception of how a basic traffic system should work.

It is absolutely not unreasonable to expect a 1993 game to not choose a random route at a junction; it should use a basic pathfinding algorithm (which were well-known, even in 1993) to choose the closest one.

Of course it is limited by performance but optimization is hardly a good counter-point to intuition in this kind of game.