I wouldn't necessarily say vast number of americans have plenty of experience outside the US.
For example, only 42% have a passport. https://www.forbes.com/sites/niallmccarthy/2018/01/11/the-sh...
For example, only 42% have a passport. https://www.forbes.com/sites/niallmccarthy/2018/01/11/the-sh...
In terms of understanding another country, I'm sure we can agree that there's simply no substitute for living there, working there, and speaking the language for an extended period of time.
In a very distant second place, there's having friends, family, and colleagues in other countries. I'm middle aged and my grandparents live in the Netherlands. Unfortunately I've not been able to travel there, but I do have several decades of secondhand experience with their healthcare system so I, at the very least, know there are viable alternatives to what we have in the U.S. in terms of healthcare and lifestyle in general thanks to them and my close friends and colleagues from other countries.
In an even more distant third place, there's tourism. I wouldn't call it a waste of time, but I don't think a week or two of sightseeing and Instagramming it up teaches the traveler much about life in that country.