A4 paper doesn't fit well into typical folders and binders sold in America, and I didn't see A4 paper at all until I went to another country for a while. US uni

A4 paper doesn't fit well into typical folders and binders sold in America, and I didn't see A4 paper at all until I went to another country for a while. US universities tend to just have the printer set to scale pages to fit the paper by default. You end up with wider margins when printing A4 journal articles to Letter paper, but those can be handy for notes.