On the subject of X% of Americans not having passports, there’s a reason for that....
If I live in, for example, Ohio and I want to go on vacation, I have many options :
If I want to go to the beach, there’s Florida, Hawaii, Southern California.
If I want to go skiing, I can go to Colorado.
If I want to visit the big city for a dose of Culture or sport, I can go to New York, Boston, LA, San Francisco etc etc.
If I want to visit national parks to trek and spot wildlife, the US has the some of the best in the world.
If I want wilderness, there’s plenty of that in Wyoming or the Dakotas.
If I want to gamble, I can go to Las Vegas.
If I want to see Polar Bears I can go to Alaska.
Etc etc etc...
Why do I need a passport?