The words "Clutching at Straws" come to mind.
If one says to one's wife "I am going to make an investment that gives me $10,000, and I will give you what is left after tax", then that may bring an appreciative smile to her face .
But if one says to one's wife "I am going to make an investment that gives me $10,000, and I will give you what is left after tax........ and after I have deducted the $8000 in interest that I will have paid to get that 10,000", then may I suggest that the appreciative smile will quickly turn to something rather nasty - since plainly, anything she money gets from it will be trivial.
Far from making new rules up as I go along, it is you who takes what is plainly implicit to anybody else, and comes up with new interpretations that make the initial scenario nugatory.
As for the second part - if one wants to avoid paying the ATO $3450 or $4900 dollars by giving several hundred thousands of dollars to one's wife, then that is fine. That is no longer one's money. But I like keeping my capital.
Regards,
Renato