[snogglethorpe]

Even Google maps in Japan way overemphasizes highways and other roads, given that they're less important than transit in places like Tokyo.

You can tone down some of road-overemphasis by selecting the transit option (路線図) in the side-menu, but this really should be turned on by default in Japan. [Using this option is also a little annoying because it highlights subway lines in rather garish colors, while (equally important) surface rail lines keep their ordinary subdued appearance.]

I dunno why they do things this way, but I suppose a lot of the tech and know-how came from the car-obsessed U.S., and probably a lot of their Japanese data comes from road-atlas companies (who have a reason to emphasize roads).