The population density of Italy 201/km2 is lower then population density of Germany 241/km2, so from point of view of density, Germany should have more high-speed rail than Italy.
But because cars are major German export driver and car manufacuring is major employment in Germany, anything competing with cars has not much political support.
https://www.dw.com/en/germany-merz-pledges-to-resist-2035-eu...