You've moved the goalposts again
Your original comment: "ATO is always going to be a much better source of income information, as census only asks about the last week vs a whole year" was completely wrong. I define 'usual' as the common-sense, plain reading of the word, for the individual concerned. It completely takes into account variable income. Investment income, share dividends etc of course are captured if you work on the annual income option.
If 'usual' means different things to different people, so what? There are lots of words in the census - and in every day conversation - that are the same. Just answer for yourself and it'll be fine.
But I suggest you read the actual census question before commenting further.
Your income during covid isn't usual. So what? Census questions are not popped in and out depending on whats gone on that year, they are constent census after census (
unlike tax laws, and income tax requirements), with questions added or dropped only after significant consideration. If its an anomalous year, then guess what? The census will record it as such, and we'll see the effect of covid on income though various professions, various areas, various ethnic groups etc. Who's affected most? Least? etc.
Again, just
read the census question. And have a look at the comment on the form about the background to this question.