Well, my suggestion, isn't Completely correct,... but is Mostly.
ISRA run a Teams Class that uses Flexi type chassis (recently the JK Aeolius) but Run a 'Specified' Sedan type Body.
Handout tyres, a fixed gear ratio and Handout Group 12 motors.
Whilst that chassis is popular here, it is usually run with some kind of 'Tin Can' Sealed motor like a JK Hawk 7 or similar as in the GT-1 class.
As to why Australia never really 'got on board' with the general Euro Sport style of racing, is a good question but probably has a lot to do with Cost, the type of alternate affordable classes that were already running and popular here Plus the fact that we were probably intrinsically More 'aligned' with what was raced in the US more than in Europe or the UK.
Womps, Flexi's and various 'Wing' car classes were always very popular here, Group 20 being almost a Mainstay of Australian Wing car racing, along with (eventually) Group 27, alongside Open class racing.
Eurosport chassis and equipment by comparison, was somewhat limited in source and options, chassis and motors were/are Not cheap (which is why there is currently such interested in Brushless) and I think the Eurosport development also came at a time when Slotting was at a low 'Ebb' here and it was Not an affordable or easy Option for New racers or track owners.
Far easier to maintain what was already popular, affordable and well known and accepted cars/classes that could be used and raced everywhere in Aus'.
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