Richest Kiwis pay about half as much on the $ as the rest of us

[R2x1]

Don't hold your breath waiting for a change. We've known about this for decades and nothing has been done to change it. And nothing will...

Changes to laws depend on the legal profession, who definitely do not profess to be in favour of themselves having to pay more tax, simplifying the law or reducing their billable hours in the slightest degree.
"There's no facet of human misery that lawyers cant make a good living from."  Tax payments qualify as vigorously generating misery, so the profession will not at all  be in favour of fairness, transparency or simplicity in tax collection.
They are more likely to propose a Royal Commission, so-called because the taxpayers will pay a King's Ransom for the endless rort.