I am not sure if this has been posted already, but I reckon it deserves its own thread to create awareness.
Around 4 years ago, an article was posted on CarThrottle about a
tax relief system for UK gaming developers. The way it works is that the more British a game is, the more tax game developers would be able to reclaim (see chart below):
When this was announced, development for Horizon 3 in Australia was already underway so it would make sense for the next game to take place in the UK to take advantage of this tax relief. It also explains why there are so many more British cars and could point towards the "Horizon Life" being themed around British culture.
If anyone wants to post this on Reddit to educate the disappointing lot wishing for a game set in Asia, go ahead.