V8 supercars is a marketing exercise, not a sport. That Holdens sell better than Fords and both sell much better than Magnas comes down to the marketing for V8 supercars. As for Holden being all Australian - not since General Motors bought in - i.e. before they ever built a full car.
On the racing side of things - the Ford and Holden marketing departments could see the overseas tourers coming in every year and taking the prizes. The Nissans were unbeatable, except possibly by the Cosworths (assuming they could lift their game). But the marketing lads could see that sales of ricers would increase and the big "family" cars they were tooled up to produce would drop - meaning lower profits. And if it weren't for the V8s I doubt the Falcon or Commodore would exist. More people would buy "smaller" cars.
Sit in a 60's Ford/Holden again and tell me you can't get the same (or rather, more) interior space, comforts, speed and handling from a $20,000 Korean :twisted:

