Technology that lets outdoor advertisers track people in the street is spreading, though the marketing industry says it is at pains not to invade privacy.
The country now has at least 1400 digital billboards and screen-posters, many of them with smart technology.
Highly-targeted advertising is common online and outdoor advertising is playing catch-up.
Several major agencies are getting location data about consumers from cellphone tracking, but they mix it all together, or aggregate it, according to an industry report.
At least 49 billboards have cameras that count cars by recognising their number plates, but they do not identify their owners, according to owner Lumo.
Meanwhile, Westfield shopping malls have 126 SmartScreens that can detect faces and even gauge what mood a person is in - but not who they are.
The advertising, tech and retail companies at the leading edge of the digital expansion said they were not gathering or processing any personal data, or it was all anonymised, and that they followed all privacy laws.
"The business has no interest in the movement of individuals," said Canterbury's Go Media, which has digital billboards in the three main centres.
"Rather, Out-Of-Home [OOH advertising] has always been used to deliver advertisers' marketing messages to large volumes of audiences."
Go Media used a mobile GPS platform that gave it "down to the hour" data for each digital screen about "customers' real-world behaviours, brand affinities and purchase habits" - but none of that had identifiers attached, it said.
The GPS platform is from Australian firm Landmarks ID.
It has a deal to access the location data from the phone apps of more than 80,000 members of the leading consumer loyalty scheme, AA Smartfuel.
Members were only enrolled if they explicitly opted in, AA Smartfuel said.
"I founded Landmarks ID as I saw a lot of bad actors operating in the data and insights space, sourcing datasets without the consent of the consumer and/or data owner," New Zealand expat now based in Australia James Fogelberg told RNZ.
His system was accurate to within 5-10 metres and turned on 24/7 - but no personal data was collected.
"By building an insights company off anonymous datasets, valuable insights can still be provided," he said.
This is a theme that is repeated across the industry.
Just how invasive the tech moves are or might become, has been downplayed or difficult to gauge.
The ad industry in New Zealand has played down the technology's personal reach in public statements, and played it up in promotional material that trumpeted its ability to deliver "rich first-party customer profiles".
A big billsticking company Phantom, for instance, when it signed up to Landmarks ID, said: "Audiences are measured from their home or work, to the moment a Phantom poster is encountered, and then onto a retail location ... bank or restaurant."
In practice, though, Phantom said it was not using the technology much.
Warnings about the advertising tech's reach have flared in overseas media for several years.
Sceptics speak of "surveillance capitalism", a wide-ranging term coined by leading critic and Harvard Professor Shoshana Zuboff, who said it "begins by unilaterally staking a claim to private human experience as free raw material for translation into behavioural data".
US public radio NPR carried a report in 2020 of getting its own advert flashed up on a billboard in Times Square, New York, where the reporter said it was a "magic trick" that the billboard's built-in sensors could tell what cellphones were near.
But the desire was to snare masses of eyeballs "rather than the movement of any one individual", said Mike Watkins, the New Zealand head of multinational ad company JCDecaux, which helps run Calibre, an advertising measurement tool that is powered by Landmarks ID.
Despite the talk of a "rush of technical innovation" from Go Media, not everything has been gung-ho.
For instance, while the billboard number-plate cameras could be used to collect data on the age and gender of motorists - it was "in the pipeline", said the ad industry report. Lumo had pulled back from that, said co-founder Phil Clemas.
"That's become too difficult," he told RNZ.
"It really begins to impinge on the privacy legislation, so we want to stay away from that."
The data would not be that useful to them anyway, he said. A tech advance that allowed them to measure the "dwell time" of a motorist in sight of a billboard was better.
Some clients wanted to know vehicles' make and model, and bought that separately from data brokers, Clemas said.
The basic vehicle registration data is available free from NZTA.
Out of your car and into the mall, where Australia's Scentre Group has 126 advertising screens smart enough that they can tell just how many of the 36 million visitors to Westfield centres each year have taken a look at them.
"These technologies meet New Zealand legislative requirements and do not identify individuals, or record or retain the images of individuals," Scentre said.
The counts the screens provided helped brands and businesses "reach our visitors, at scale", it said.
The screens can be programmed to go further: Their supplier, French company Quividi, ran a trial for carmaker GMC outside a mall overseas where a mini-billboard swapped out the three dozen videos it was programmed with according to reactions from passersby caught on camera.
But this was not facial recognition, Quividi said. "Think of it as a smart turnstile".
A bigger growth area was in cellphone tracking, which could include geo-fencing around a billboard or poster site that was triggered when phones crossed it, or wireless "beacons" that used Bluetooth to send and receive signals from nearby smartphones.
"Mobile GPS pinpoints devices travelling through a geo-fenced viewing corridor of the billboard," the industry report said of Landmarks ID's system.
"Data is collected in real time across all modes of transport throughout the day."
The report also said customer location data sources for the various systems included Spark subsidiary Qrious, rival telco 2Degrees, and Westpac Bank.
Qrious told RNZ this arrangement ended some time ago.
"Qrious was aware that the data it provided would help towards measuring the effectiveness of outdoor advertising, but it was also very clearly provided on an anonymised and aggregated basis only - meaning it did not contain personally identifiable information," a spokesperson said.
2Degrees said it "only ever provided data once, more than five years ago" in a trial that never advanced.
Westpac said it had provided an analytics company with aggregated and anonymised card transaction data "for the purpose of creating market research insights", and the company, Datamine, had previously provided this to the advertising industry.