"Us" in this case is Canada, and we've had polymer notes for years. And it's not at all unusual for people to still call it "paper money" because it had been paper for so very long. Heck, we still call the stuff we use to wrap and protect things "tin foil" even though it's been aluminum for my entire life (and new consumer electronics were still being made with vacuum tubes/thermionic valves, with tube testers in every hardware and drug store, when I was a kid).