Just because the background isn’t what we want – who says we can’t make it so? Your vehicle can be traditionally light painted in your location, but be put where you would have wanted it to be!
Also we rely on compositing when photographing a project in a less than optimum location, in a storage building for example. Or when a subject has too many awesome details or angles that just 1 can’t be decided upon. Then a composite showing the many stellar views of a vehicle is created!