Unfortunately, I have to agree with the comments above. No matter how much effort an organiser puts on, its the public that will ultimately make or break an event. They are the ones who will provide the return on the eventholder's (and sponsors') investment. The past events havent been the best, but that is expected for such a new enterprise.
As for competitor numbers, I see better fields at some Wednesday night Street meets. If half of the competitive cars in Sydney alone turned up it will be one hell of a competitor list. What these events rely on is actual consistent and competitive drag racing so that the fans actually want to attend. Then there are the sponsors who invest in such events, but will only do so if they get the return on their investment. Without the public, this wont happen. Its a bit of a vicious cycle, but that is the nature of this beast.
Another important factor has been the teething problems associated with setting up and formalising the rules and format for SC.
I sincerely hope that SC drag racing will only get bigger and better.