I am constantly astonished by the American habit of not having a passport.
It certainly explains the parochial attitude so many Americans display, as exemplified by the usual response from Americans to this astonishment, that "America is so large and diverse that it's not necessary to travel overseas in order to properly experience other cultures", which is the kind of utter drivel you would only hear from a parochial hick who never bothered to find out just how large, and how diverse, the world actually is.
Over here, it would be rather surprising to discover that an adult acquaintance did
not have a passport.
Remember, the US is much, much bigger (population wise--you have a lot of empty land but people don't go there) than most countries. You can easily experience quite a variety of things without ever leaving the country.
Yeah, lots of Americans say that.
It remains untrue - all of that variety is of the "big fish, small pond" type, that you can get in any country. And this belief that America provides sufficient variety to understand the other 95% of humanity without visiting their homes is not only false, but dangerous, given that the USA is global hegemon.
It's a very long day's drive from here to the closest border--and that's a border I would not be willing to cross for safety reasons. It's multiple days to the other border.
It's a great deal further from almost anywhere in Australia, to almost anywhere outside Australia. We don't even
have a border you can
drive to. But an overseas trip is nevertheless a rite of passage for young Australians, and an Australian adult who has never owned a passport is incredibly rare.