The reverse z order mentioned in the article confirms what a friend of my wife who ran marketing for a regional chain said: the top right item on the first page will be the highest margin dish, normally pasta.
For years I would look and she was almost always right.
Japan and China both read left-to-right, just like we do. While some traditional texts are written vertically with lines proceeding right-to-left, that doesn't really carry over to general UI conventions. A set of three horizontal images would typically be understood as proceeding from left to right, for instance.
Arabic and Hebrew, on the other hand, are primarily RTL, and this does carry over to UI conventions. Menus might be laid out differently there.
Many soba restaurants use vertical text written right to left because it gives a sense of old times. Higher end traditional-style restaurants do this too.
Family restaurants and anything with western food is pretty much always written left to right.
It's also very common to see street signs (notably "construction ahead" and "beware of __" signs) using vertical right to left text.
Manga is normally right to left (both pages and lines) because it's written with vertical text. "learn statistics through manga" type books are left to right because they're written with horizontal text (because of formulas, etc.).
(I don't know if I agree with the comment you're responding to, by the way.)
It's irrelevant for computers because text on computers is basically always left to right though.
Horizontal text in modern Japanese is virtually always written left to right.
The primary exception is where the context of the writing itself implies a direction, e.g. text on the passenger side of a bus, or on a directional sign pointing to the left, may be written right-to-left so that the text "flows" in the same direction as its container. This would never be used for a longer text, though.
In Mainland China reading direction is mostly left to right, top to bottom now, just like in most European/American countries. I should go and see if the top right menu item is the one with the highest margins.
Only if by "western knowledge" you mean Communist Internationalism and its associated obsession with conformity. The change to left to right horizontal wasn't a natural development, it was forcibly imposed during the 20th century by communists. Given a choice people still prefer vertical (most novels and manga outside the mainland are still typeset vertically). It also has nothing to do with "technology". The first Japanese typewriter used vertical typesetting[0], websites in the Mongolian script use vertical typesetting[1]. It's sad to see people use technology to justify a global monoculture.
For years I would look and she was almost always right.