Its probably just where they built the plants, their scheduling,
plant capacity, local taxes, labour rates, proximity to a port,
etc.

Honda Accords and Toyota Camrys are built in Japan or the U.S.
(I ownder if buyers prefer one over the other?)

There are a couple of books that cover the History of Volvo that
might talk about the various plants. Might search on Volvo at
Amazon.com. I have one (a Christmas gift) but don't recall the
title (it mostly covers the history of vehicles).