High volume Japanese mainstream models are from Thailand , Indonesia or locally made/assembled.
Another thing you have to consider, VW does not manufacture small sedans in Europe.
The only way they can have something priced like a Vios is if they source it from an Asian plant like the one in China.
VW was able to move their old German and Mexican model here because of heavy 6 digit discounts. Factor in TRAIN and those Euro and Mexican models would have become even more expensive.
China and Southeast Asia are more aligned in terms of model offerings. The Toyota Vios which is not made or sold in Japan for example was developed with Southeast Asia and China in mind.