Story time. I travelled to England and Scotland with my parents when I was a teenager. When people would as where in the states we were from, we answered Washington, DC. We were actually from Maryland, outside of DC, but figured DC gave foreigners an easier general idea what part of the country we were from. I would never assume a person from outside of America remembers, even if they had learned it, where the state of Maryland is. Anyway, we are sitting in a pub in Edinburgh, a very nice gentlemen sits by us and strikes up a conversation, asks what part of the states we are from, and we answer DC. He replies, “my brother moved near there 17 years ago, he lives in Gaithersburg, MD.” We lived in Gaithersburg! I graduated from Gaithersburg High School! Who’da thunk it?!
To answer your question, it is a little bit of ethnocentrism, the US must be the center of the world, isn’t it? We, as Americans, are also constantly told we suck at geography and everyone else in the world is so much better, how come you don’t know where Memphis, TN is?
But, seriously Americans do this to other Americans. If you asked 1,000 east coast Americans what time zone Memphis is in, I bet less than 100 would know for sure. If you tell them it is west of Chicago (pretty much all Americans know Chicago is in central time) they would answer with a, “really? I didn’t realize.” Americans when asked where they live almost always have to clarify for people who live out of state, again even within America. A new Yorker might tell someone from another state, “I live in NY.” some might assume NYC, people from the area would ask, “what part?” meaning what part of the state. People ask me what part of FL I moved from, I many times say South East FL, rather than a specific city, if someone wants to know the city they ask. If I say the city as my first answer, then they typically ask, “what part lf FL is that?” I emphasize again this is American talking to American.
Our country is huge. We have many states with the same cities. What I mean is there is a Raleigh, Norh Carolina, and a Raleigh, TN, and Westchester County, NY and a Westchester Michigan, it is complicated, don’t ever take offense or feel uncomfortable having to ask for clarification, we Americans have to clarify American cities for ourselves.