> because the number of passengers and the number of trains is also so numerous!

I don't think the author's hypothesis, that complaints scale with utilisation, holds.

Germans travel fewer kilometers per year per capita by passenger rail than Japan, Switzerland, Austria, Hungary, France and Korea [1]. The two topping that list–Japan and Switzerland–also have exceptional systems.

[1] https://en.wikipedia.org/wiki/List_of_countries_by_rail_usag...