I'm not sure which state you live in, but there definitely is a club system for athletes to continue on post-school in Victoria, NSW, South Australia and Tasmania - not to mention regular road races.
You're right about no one discussing athletics, but that's true for all Aussie sports outside of AFL, rugby, cricket and maybe horse racing. The demographic that frequents pubs is probably not the same as the one that's going to attend a cross-country race or a Vic Milers meet.
The point I was making was that Australia is pretty good at introducing kids to the sport. Talented athletes, at the very least, get exposed to the sport, and if they're interested, will receive good guidance from senior athletes. The system is much weaker for athletes entering the senior ranks, however, where, unless someone is extremely passionate and/or extremely talented, they're likely to lose interest. The NCAAs seems to have filled this gap for those that are talented enough to make it though.