Hmmm....it could be that a lot of America is the same all over...a sort of homogenization seems to have taken place...but perhaps you're discovering something more. That is, even the independent places strongly resemble each other, like there's a sort of fractalness to it: "all funky coffee houses resemble each other" and that all old-fashioned diners look very similar. Maybe, say, in the case of a coffeehouse, people who start coffeehouses do so because they really liked one they went to, and so the one they create contains the same elements as the one they liked, and if that holds true for most people who start independent coffeehouses then maybe a population of "funky coffeehouse owners" develops that shares a certain eclectic style--eventually developing into some "norms" for such coffeehouses. When someone visits for the first time a coffeehouse in a new city they probably compare it to their favorite "back home" and it gets higher marks the more it resembles that favorite. And this tends to reinforce the "type." When I ran a used bookstore for a couple of years I was careful not to stock books that were mildewed or moldy but then people would come in my store for the first time and complain that it didn't have "that old bookstore smell I love." My explaining that the smell they loved was due to dust and mildew and that I was trying to run a clean, well-lighted place, did not seem to satisfy them. Based on their past experiences they had a model in their heads of what a used bookstore had to be, an expectation, and I had failed to meet it. I could tell they felt my store did not measure up.
Then too, all restaurants resemble each other, really, because they all generally have tables, chairs, etc. Maybe if one sees enough places differences tend to be obscured by our perception of the common elements. If I'm sitting at a table on the dock at Nantucket eating oysters how different is it from sitting on a dock eating oysters at a little place on the Rhode Island shore? In both places I'm sitting next to the ocean, on a wooden dock, at a table, in a chair. The oysters may even have come from the same beds....it's possible. The places are very similar but the building I'm sitting in in each case is distinguishable, the waitresses are different, the details of the view are different--in Nantucket I look onto a harbor scene with yachts and ferries coming and going. At Rhode Island the view is smaller, a cove, with private homes and small personal docks. So, very much the same, but different in detail. Maybe being on a long journey such as this one, the experiences begin to bleed into each other, to blur somewhat, and the details get filtered out in the process because the common features are sensorily reinforced and fill the memory. Or it may be that humans become overloaded with novelty after a period of time of unceasing change and so we mentally grab hold of the common, familiar elements....to sort of ground ourselves. But if this were the case one might expect it to be a comfort and it doesn't seem to be that to you, so I'm going with the other idea...that subconscious awareness to the common elements tends to crowd out the details, in time. Don't know if this is balderdash or not....but if not for your insightful RR, Anti-hero, I wouldn't have paused to ponder.... so thanks again for making me think!!