Google's IP to location mapping is so bad it has to be intentional. I was in Japan and using my home network as a VPN quite a bit, after a while Google decided my home comcast IP had to be located in Japan. Even though others in the household were still there, they started getting default-Japanese pages on google/maps/youtube/... It didn't fix itself back until a couple weeks after I got home, even filled out https://support.google.com/websearch/contact/ip
I'd be more willing to bet that it's because my GPS location is in Japan, which is the strongest signal of my physical location. Nevertheless, my home IP is used by multiple people, they probably know who they are and that they're not in Japan. My own signals are a mix of VPN'd/non-VPN'd apps on my phone and laptop (not strict about the VPN, some Japan sites require a Japanese IP), and I do often NoMachine back to my home machine and access google services just like I do at home.
