But that still doesn't change the fact that path finding must necessarily occupy a larger and larger fraction of the cpu time as the player builds a larger and larger city. Each path becomes longer, there are more paths to plan, etc. In order to maintain an acceptable frame rate in a large city on the minimum spec computer at the time of release, Cities: Skylines has a fixed limit of 16k moving vehicles. This caps the time spent path finding as well as maximum frame time because once the vehicle limit is hit, agents start teleporting rather than being forced to traverse the map.
But we got thousand times faster CPUs than at Sim City 2000 times.
And they have multiple cores. And if that is not enough there are GPUs with even more compute.