I gotta say I never understood this problem either. But it works for me. I live in the USA. My spouse is from Japan. If we log into Netflix Japan through VPN on a laptop, every instance of Netflix shows Japanese subtitles. Absolutely wonderful way to make spouse happy!! We can disconnect the laptop from VPN and still get subtitles for a month or so.
I gotta say I never understood this problem either. But it works for me. I live in the USA. My spouse is from Japan. If we log into Netflix Japan through VPN on a laptop, every instance of Netflix shows Japanese subtitles. Absolutely wonderful way to make spouse happy!! We can disconnect the laptop from VPN and still get subtitles for a month or so.