> In Germany we have no spot that can not be reached via car and foot in a day.

I know this story was about Idaho that has, at least today, relatively fewer places that are completely inaccessible. But if you go to Alaska, there's enough territory that's inaccessible by car that is 3x the size of all of Germany (that is, I think there's well over 1 million square kilometers of inaccessible places in Alaska).

The lower 48 is much less so, especially today. Still if you get up into the mountains, in the crazy wetland areas (parts of Florida everglades, parts of extreme north Minnesota, etc), it can get impossible to traverse by car, and very difficult by foot.