Earlier quoted context omitted.
> seems confusing if so It is no more confusing to Americans than the fact that Europeans use A4 is to Europeans. Why should it be? Just like you didn’t know standards other than A4 exist, Americans don’t think about the fact that standards other than 8.5x11 inches (I.e. letter) exist. All printers, binders, folders, hole punchers, etc. are made with letter size paper in mind, and most people unless they are involved…
> It is no more confusing to Americans than the fact that Europeans use A4 is to Europeans. Why should it be? Well, A4 (and variants) are not Europe-specific formats, it's the formats most of the world except some few countries (including the US) use, so I'd say it's slightly more surprising than the other way around.
Even if every other country in the world used A4, the only people in the US who would even notice would be people who commonly do business with other countries or who live near the border. And in reality, Canada and Mexico also use letter so the border thing doesn’t apply.
So why should letter confuse us just because other people use something else?