A traveler need money changer to exchange the notes to the desired country banknotes. Before that usually we find out the exchange rates first on the Internet to get roughly estimate about current rates. We seldom think about the notes design and appearances.
Of course they are people who appreciate bank notes from around the world and they follow updates about world bank notes. This people not necessarily bankers or finance guy, this is some kind of hobby. Ebay is common place for banknotes collectors to find rare and old notes around the world. The website banknotenews.com got plenty of world banknotes updates from enthusiast.