A far greater proportion of the US lives within 100 miles of the US's international boundary lines than vote in US elections. No matter how someone may try to slice that, the fact remains that the great majority of all US persons live within 100 miles of an international boundry and can get to another country relatively cheaply if they wish in this land of plenty of miles and points.

The probability that a US-born US citizen has traveled to a country on another continent is far lower than is the case for citizens of most other OECD countries.

It's not quick and easy to find a Swedish-born Swedish citizen (of non-immigrant roots) who hasn't had at least one immediate family member go to Thailand; however, that hasn't done anything to spare SAS from being on the decline and losing on its scheduled service to Thailand.