I think the old adage for writers is to write about what you know, and most American don't know that much about the rest of the world. I'll admit that I have included trips overseas in one on my stories (to the UK, Australia, and Japan) but I had to do one hell of a lot of research to pull it off. I had spent time in the UK when I was young, but things have changed there and my memory isn't as good as it once was, therefore I had to do a considerable amount of research in order to pull it off, but as I did I tried to explain as much as possible so every reader could enjoy it as well.
Since this situation was brought to my attention, I've tried to make allowances for this. When using feet, yards, and miles, or ounces and pounds in my stories, I try to include the metric equivalences. When I'm talking about high school or college, when I use the term freshmen, I put (1st year) behind it, and sophomore (2nd year), Junior (3rd year), and senior (4th year), but now I see it might be more useful if I included the character's age. I try to make my stories as interesting as I can for anyone to read, no matter where they're from, but I'm learning there is more I can do to accomplish this. Thank you for sharing pointers, aswell as your viewpoints on the situation.