I found it, just to put it to bed. It is a National rule, but it is interpreted differently between states.

https://www.yingtongli.me/blog/2019/06/16/arr-roundabout-exit.html

I wished that the link was more from our government, however I followed up the National laws this posts states, and they are indeed correct. Australian Road Rule 118 says it is required (in any circumstance) but only if practical. And that seems to stem from Vic and other states with larger 3 or 4 lane roundabouts (which would suck).

The post also comments: A casual search of internet forums reveals many confused drivers believing that this is optional, or is not a road rule, or is, indeed, a silly thing to do. From personal experience, the vast majority of drivers do not indicate left when leaving roundabouts. The law, however, is clear that a left change of direction signal must be given when leaving a roundabout, ‘if practicable’.

So I'm happy to indicate left on leaving the roundabout, it doesnt bother me anyhow. But it would be a total headache for Tesla drivers, and my indicators are on my wheel and not in the right location at the time, would not constitute as "impractical" as far at the process. The car might be impractical, the the process should not have been,