due to all the 20th century conflicts
I assume he’s referring to the same question I was asking: did you just extrapolate this from the phrase “fucked up, disastrous mess” (referring to the sheer number of different systems in Europe?), because I think the big long reply above seriously undersells the fact that “20th century conflicts” aren’t even mentioned or gestured at in the video. There’s a map showing…different countries…but while 20th century conflicts changed various borders in Europe, they aren’t the origin of the borders between countries in Europe, or the origin of different European countries developing their own independent rail systems without any centralised plan - because they’re different countries, and the various bodies which today unify much of the continent only began to come into existence after the Second World War.
If we were talking about Former Yugoslavia, you’d actually be right! The integrated rail infrastructure of that region was completely devastated by the 1990s. But that’s not the focus here.
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).