But why does it need to change? Would NZ really be better off if it got to tax the NZ revenue of Australian companies operating in NZ but gave up being able to

But why does it need to change? Would NZ really be better off if it got to tax the NZ revenue of Australian companies operating in NZ but gave up being able to tax the Australian revenue of NZ companies operating in Australia? Given that Australia both NZ's largest trade partner and much larger (and somewhat wealthier) than NZ, isn't it likely that quite a lot of NZ companies earn significant amounts of revenue in Australia? Would NZ even come out ahead from such a change, even ignoring the (very significant) costs of a massive change to the tax code? Because offhand it doesn't look like it.