Italian Sandwiches

Ok so 5 years ago I came to maine, and early on went to a convenience store and purchased what I thought would be a sandwich that had salami peperoni etc and other italian meats on it with some leuttece and cheese and shit. To my dismay it only had ham and veggies, I would later find out that in Maine as opposed to almost any other part of the country that that is referred to as an Italian. So the other day Im in subway and some classic BMW(if you dont know what is you afford cant feed it) walks in and looks at the subway worker and simply says in a raging accent "uuuhhhhh, I think Im just gonna an Italian" the subway worker then asks if she wants the spicy Italian or the Italian bmt, the woman replies no I just want an Italian, this back and fourth happens once more before the, now, somewhat enraged Maineah starts to lecture the subway employee on what an "Italian" is, like it is offensive that the subway worker doesnt instantly know what she is talking about. My question is how did people from maine get the idea that an "Italian" sandwich was italian because of basically the type of bread olives and oil and vinager? And why has it not caught on anywhere else in the country?