“Afaik, America and Europe both primarily use standard gauge, so I don’t know what this is about.”
One meter narrow gauge is MUCH more extensive in Europe than in the USA where narrow gauge is almost exclusively used for excursion routes.
Narrow gauge used to be used in lumber camps and trains all over the country. It was easier to get trains to traverse twisty and windy switchbacks in the mountains on the way to the timber harvest.