Why does a train does not run on normal road, other than railway tracks?

Why does a train does not run on normal road, other than railway tracks?

I’ve never really thought about it. But a train track provides pothole free support along the entire length of the path. I suspect it would be financially impractical to produce roads capable of supporting the loads and allowing the train to roam freely. The track is a reliable/relatively low maintenance driving surface.

Of course we could design a train with larger contact surface area to distribute the load, but as surface area goes up, rolling friction forces also go up.

I see another advantage of the track system. It enables an engine to pull or push. Without the track, an engine could only pull the train. Good question.