404, I fail to see that CAO82 doesn't apply to charter or airwork. It may be a general requirment as you say, but is nonetheless applicable despite it's generality. As the title clearly says in another's earlier post
This Part applies to Air Operators’ Certificates authorising aerial work operations, charter operations and regular public transport operations and sets out conditions to which such certificates are subject
Sure 3A is only applicable to charter, but adds to the requirements of CAO82.
Seeing CAO82 does apply to these sorts of operation (otherwise why would it be in the title), then certain requirements have to be met - and they are, as per para 2.3 (a) a certain amount of fuel as approved by CASA and in the ops manual ,or, (b) an alternate irrespective of the weather.
No, an alternate is not always required as there is a way to avoid this (para 2.3 (a), however I would summise that most operators taking advantage of this would probably require more than just the 10 or 15%, 30 or 45 minutes for such operations, possibly some Island Reserve on top. The general requirements of CAO82 nonetheless apply irrespective of a which fuel policy and irregardless of it being RPT, AWK or CHTR.
If they had meant for the rule to apply to AWK and RPT ops it would have stated it in subsection 3A.
It is stated, in the applicability preamble to CAO 82, quite clearly. By extension of your logic, then RPT could be done in a single to a remote island, because it isn't stated otherwise in that section - just that a charter has to have >one engine. We all know that is not the case. As has been said elsewhere, you have to read all of the CAO and not selective pieces.