In a very real sense.. the ‘real world’ we know doesn’t exist, especially as things got bad enough on Earth that there was severe flooding of the coasts (which is why Venice was sunk in the first place, and parts of it were relocated to Mars – and the glass-blower chapter notes that the population of Venice had to be scattered because they couldn’t be relocated wholesale to anywhere else and have another city plopped down there), and most of the cultures there… well, they don’t exist the way we know them, so saying that Kozue Amano has Japanicized them for easy consumption of her viewers is a facetious statement – most of those cultures don’t apparently exist on Earth either, except in recordings (Akari mentions this during the Fox Bride wedding story, that she’s never seen real temples) and for the most part is surprised by the fact that Neo-Venezia has so many festivals to begin with. It sounds a lot like Earth of ARIA’s timeframe is more like Anglo-Americanized version of our present-day Earth, with a few clothing customs kept but otherwise relegated to the dustbin of history due to the massive societal and economic changes which had to occur as a result of what sounds like an environmental disaster on a grand scale with the resulting effects that mass-scale population dislocation would result in (cramming people together in cities, mingling distinct cultures until they were no longer distinct, and the domination of one set of viewpoints over most others).

Look at the tourists who show up in Neo-Venezia, for crying out loud – they’re all dressed like Americans or Europeans, sorta like present-day Earth, but more so. They’re mostly WHITE people, to boot, or at least nobody seems to possess skin colors with any range among the tourists. At least with Neo-Venezia, if it’s a reproduction of Venice and Italian culture (or what was left after it was forcibly fused with other traditions) which explains some of their uniformity… and that same forced fusion explains things like Japanese traditions being integrated (besides Kozue Amano wanting to make the story more accessible to Japanese readers by introducing things that they’d be familiar with).

The setting’s there to show off the characters and their relationships (along with Akari discovering a world which is distinctly more alive than the one she left; her comments suggest that Earth of her time is very ‘nice’ in the cities… but very bland and uniform, and not at all lively or spontaneous or even prone to doing things that aren’t efficient and quick) – it’s not the cake, but the display on which the cake is presented and served.