ONE of the key aims of taxation and public spending is to redistribute income from rich to poor. The way most statisticians, economists and policymakers think about this is in terms of a cross-sectional snapshot: what the distribution of wealth or income is between different people in a population in a single year. But we might care more about lifetime incomes: in the modern labour market, many people now have very high incomes in certain parts of their lives, and much lower ones at other times.
NZ's Gini coefficient is very similar to the UK's cross sectional so it may very well be similar to their lifetime. I can't think why it wouldn't. In which case inequality may be declining.