I’m one of those people. Japan and China are quite different. I really liked visiting Japan. I really did not enjoy visiting China at all. The two cultures are not as similar as you imply, and the differences matter, at least to me.
If you are just visiting, you won’t see much similaries. Japanese also consider non Japanese (or more precisely, non Asian looking), to have different norms than us so we treat them differently. Its an internal barrier that homogeneous society make. We will be polite about it but forever we will consider you a foreigner.