As much as we humans are all part of a “global community” more than ever, there are still lots of differences between us. Where you’re raised usually plays a big role in how you’re raised and therefore how you present in public, since the social norms of different areas of the world (or even of different parts of the same country) can vary greatly.
Fortunately, more and more people are able to travel nowadays. With so many differences between us, on top of the stereotypes that arise from those differences (loud, obnoxious, demanding American, anyone? [I can say that; I’m from the U.S.]), there’s bound to be some finger pointing in terms of who the worst behaved tourists are.