Hence "as distance grows"...

But a 1000km radius around any major center in Europe covers a lot of potential destinations. I assume that a lot of people, especially in the US underestimate the density of Europe.

1000km is a stretch to set the threshold at which trains win on time. It is also costly, not least when you hit a mountain range... at some point you need to balance billions of euros vs saving an hour (or even less).

Is that always true? In France HSR stations are often like airports, way out of town and you have to get a taxi in/out of wherever you're going. And the rail network seems more exposed to mechanical breakdown in general. I don't have hard data but it feels to me like trains fail or get cancelled much more often than flights do, and when a flight does get cancelled it's usually due to some major failure that'd take out trains too (e.g. power failure).