Radio New Zealand's analysis of political advertising on Facebook and Instagram has revealed sharp gender skews in who saw the ads. Of more than 500 ads run by the National Party this year, 92 were seen only by men, attracting up to 3.9 million views and costing as much as $21,000. Only one ad was seen solely by women—for a single day, at a cost of less than $100—and the party says it did not place it. ACT showed a similar tilt, with 14 ads seen only by men and none solely by women. For the Greens, the pattern was reversed: 13 ads were seen only by women and none only by men.
At first glance, these patterns might suggest parties are deliberately targeting separate audiences. But Katherine Jensen, a professional teaching fellow at the University of Auckland Business School, argues that assumption is outdated. For much of the past decade, digital advertising allowed advertisers to select audiences based on age, gender, or interests, and platforms delivered accordingly. Meta has since shifted to AI-driven optimisation. Its Andromeda system narrows tens of millions of potential ads and variations to a few thousand likely matches before ranking them, and its Advantage+ tools can automate decisions about audiences, budgets, and placement.
This makes the distinction between targeting and optimisation crucial, Jensen writes. Advertisers choose who they initially want to reach, while the platform learns who responds and increasingly delivers ads to them. A party can begin with a deliberately broad audience and still end up reaching disproportionately more men, younger voters, or people already inclined to agree with its message.
Researchers have documented this problem for years. A 2019 study found Facebook's ad delivery could skew audiences by gender and race even when advertisers used inclusive targeting. Other research found voters statistically less likely to support a party could cost two or three times as much to reach, while campaigns had little visibility into how those decisions were made. Similar pricing effects have appeared in elections abroad, including in India, where Facebook charged the ruling BJP lower rates for ads than other parties during elections.
Meta presents its automated systems as improving relevance and campaign performance, and it maintains a public Ad Library for political ads. But Jensen argues the available data is insufficient. She says New Zealand urgently needs transparency rules so that both parties and voters understand how algorithmic systems shape political messaging. Without such rules, she warns, the people who see political ads—and those who do not—may be chosen by algorithms rather than by democratic deliberation.