Do you have a source that supports this claim?

I haven’t come across anyone using Apple Maps while living in Japan, most seem to use Yahoo! Maps or Google Maps.

Outside of the US Japan is the most saturated Apple's market

It's sub par to google maps. As much as I would like to use it in Japan, but it is crappier than Google.

Noone in my circle with iphone uses it. Most of people are using Yahoo maps, which is way better than google and apple maps combined.