From Salt Lake City heading west the first metro of more than one million is Sacramento a thousand kilometers away. In between is nothing but mountain ranges running north south. The little ones only nerds and locals can name. The big one, the Sierra Nevada, which most Americans will vaguely allude to as “the Rockies.” Despite the Rockies being five hundred kilometers to the east of Salt Lake City.
Even further on the other side of the Rockies sits Denver 800 km away. It's the closest million plus metro to the east of Salt Lake. Again across north south mountain ranges.
That’s 1800 km of mountain traversing rail line that only serves Salt Lake City. And it’s still almost that far - 1600 km - to Chicago...and a mere 1200 km to New York City.
The US is vast. Europeans don’t have practical rail from Helsinki to Athens. Or Berlin to Baku. Both significantly shorter than NYC to San Francisco.