That does clarify the point, but I also don’t think that it’s true. It may well be that a major reason proposals for unified European rail never got off the ground before recently was that European countries rejected such proposals on grounds that it would make it easier for them to be invaded. But the rail systems in different European countries nonetheless developed independently, using different technology and standards, mostly (arguably) in the 19th century.
This complex process doesn’t reduce to 20th century FUBAR, even insofar as diplomatic and security considerations were involved in its evolution (and yet of course beginning in the 19th, not the 20th, century).
I still think that this represents a bias towards a military-geopolitical interpretation of history that’s not wholly sustainable, in spite of its appeal. In the Russian Empire case, I’m quite certain that that’s a popular myth, because I know that it is certainly the case that when the first railway infrastructures were being built, the political powers, administrators, and engineers responsible were as much influenced by technological and physical geographical imperatives as they were by geopolitical. The Russian Empire’s decision to use what would become the Russian gauge was multi-factoral - indeed looking it up, it appears that they were persuaded by Brunel’s own preference for a wide gauge, which was famously thwarted in the early development of the British railways.