

Yes, it is about weight. It would generally be good to reduce the amount of heavy vehicles on roads or to let heavy vehicles pay more. There are countries who have issues with more freight traffic being on the road than it should be. (Freight trains have cheaper infrastructure for long-distance stuff)

For HSR the shape and geography probably also plays a role. It’s stretched out and the hills limit the possible routes. Similar situation in Italy.
It seems countries have a harder time building mesh networks for HSR.