The state of the rail system is a good proxy because it's a huge infrastructure project that doesn't generate any immediate profit. These types of projects are done primarily to provide social value, thus it's an indication of a society that is willing to invest into improving the quality of life for the majority.
Through a postcolonialist lens this is pretty clever. Use of civilized as a term to excuse the racist and expansionist actions of one’s own country, expansion which happens to have coincided with railways being central to industrial power. Now the colonized are civilized, are we the barbarians?
Unironically thinking like that is the real ape-brained behavior.
This just seems like hand-wringing for the pitiful state of the rail system in the USA. A country can have many dense population centres separated by large distances, making HSR viable and worthwhile, but still have low population density overall - just like the USA. The only real obstacle is political will/public support.
Western China has around half the population density of the USA but is already served by a 1,900km HSR line.