The main confusion seems to come from the assumption that if it can be performed under a PPL, an AOC must not be required.
OK, for ****s and giggles I'll bite.
What aircraft operation may be conducted by a PPL as PIC but must be conducted under the authority of an AOC? Apart from solo Navs as part of training for a licence, I can't think of many.
Any thoughts on the scenarios I set out earlier?
The regulation that slices and dices the classifications is actually CAR 1988 2(7):
(7) For the purposes of these Regulations:
(a) an aircraft that is flying or operating for a commercial purpose referred to in paragraph 206(1)(a) shall be taken to be employed in aerial work operations;
(b) an aircraft that is flying or operating for a commercial purpose referred to in paragraph 206(1)(b) shall be taken to be employed in charter operations;
(c) an aircraft that is flying or operating for the commercial purpose referred to in paragraph 206(1)(c) shall be taken to be employed in regular public transport operations; and
(d) an aircraft that is flying or operating for the purpose of, or in the course of:
(i) the personal transportation of the owner of the aircraft;
(ii) aerial spotting where no remuneration is received by the pilot or the owner of the aircraft or by any person or organisation on whose behalf the spotting is conducted;
(iii) agricultural operations on land owned and occupied by the owner of the aircraft;
(iv) aerial photography where no remuneration is received by the pilot or the owner of the aircraft or by any person or organisation on whose behalf the photography is conducted;
(v) the carriage of persons or the carriage of goods without a charge for the carriage being made other than the carriage, for the purposes of trade, of goods being the property of the pilot, the owner or the hirer of the aircraft;
(va) the carriage of persons in accordance with subregulation (7A);
(vi) the carriage of goods otherwise than for the purposes of trade;
(vii) flight training, other than the following:
(A) Part 141 flight training (within the meaning of regulation 141.015 of CASR);
(B) Part 142 flight training (within the meaning of regulation 142.015 of CASR);
(C) balloon flying training (within the meaning of subregulation 5.01(1)) for the grant of a balloon flight crew licence or rating; or
(viii) any other activity of a kind substantially similar to any of those specified in subparagraphs (i) to (vi) (inclusive);
shall be taken to be employed in private operations.