It might just be those who are more likely to drive long distances are more likely to buy Tesla.Tas, NT and SA seem to support the idea that supercharger network density equates to sales, but then WA throws that out of the water.
For Tas I gather most people heading to the mainland will fly, for the NT there aren't many places to drive unless you want to drive really far, and SA has some road trip options into Victoria mostly but it's Tesla share seems to be about halfway between Tas / NT and the rest.