They make plenty of sense. o3o
Recall the kimono girls and the building architecture in certain towns in Johto. You can find Japanese culture in Kanto like with the white hand. Team Rocket is not based off the mafia, but rather the Japanese mafia (Yakuza) aaand there are a bunch of other hints I can't recall off the top of my head.
It's unknown to me what Hoenn and Sinnoh are based off of, though Unova seems to be based on the USA. I do not believe Hoenn or Sinnoh are Japan, so despite the fact they're both ambiguously white hey would seem to be a seperate race and culture.
Julia is actually from Kanto too.
We don't get a lot of info on race in pokemon. There's honestly no evidence of physical traits differing between regions, though I can't help but imagine kantonians mocking foreigners who find Lavender Town eerie.
It seems to be very difficult to travel between regions though, so my guess is most people are just in the dark about what other regions are like. Cue curious children.