A law professor says the managed isolation and quarantine (MIQ) booking system may be discriminatory, as it is revealed tech-savvy people are able to game the system to increase their chances of booking a room.
There is significant demand for the 4000 MIQ rooms.
Currently, they are booked out until the end of November, but lately only about 75 per cent have been filled.
Available rooms appear at random on the MIQ website and are booked on a first-come, first-served basis.
One woman in her late 60s said she had no chance of being able to type her details in faster than a skilled computer user.
Karen Thorp only has a mobile phone and no computer which makes it highly unlikely she'll be able to input her data faster than someone else. The rooms she does see available are quickly booked by someone else by the time she gets through the application process, rendering them unavailable.
On top of this, one man has written an open coding script that alerts users immediately to any newly available room and auto-fills their details, giving them a valuable few seconds' advantage to book ahead of others.
For those without moderate computer skills, this script would be hard to install and use.
University of Otago law professor Andrew Geddis said the equality of the booking system may be an issue under the Bill of Rights Act.
"If in practice the system is creating a discriminatory effect because people just can't access the system as quickly as others, then that is breaching the Government's legal obligations. They have to allow everybody to have a genuinely equal chance of getting spots through the process they set up," Geddis said.
"Certainly if the system that the Government has set up is advantaging the abled over the disabled, or the younger over the older, that then raises questions under the Human Rights Act and the Bill of Rights Act of discrimination."
A spokesperson for the Ministry of Business, Innovation and Employment (MBIE) said the "managed isolation allocation system is designed to give users equal opportunity to gain a voucher".
But Geddis said questions of equality came down to perspective.
"An 'equal' system for someone who is completely computer literate - knows all the tricks, can access a computer system very quickly - is going to look very different to someone who doesn't have those advantages.
"So just saying 'we've set up a system that gives everyone the same chance' - it depends on who you're expecting to use this system, or does it actually give some people an advantage?"
Geddis said secondly, the system should perhaps be set up in a way that intentionally prioritised some over others.
"There may be some people who have stronger claims to get into MIQ than others. People who have essentially been locked out of New Zealand for months and months, thereby denied their right to return, probably have a stronger claim to return than someone who is maybe popping offshore for a trade show and wants to come back in a couple of weeks' time.
"Just saying 'we've set up an equal chance for everyone to get in' begs the question of: What does equality mean in this context? And actually, should it be an equal system? Or are there legal obligations for some people to be treated preferentially, to be given places because they've been locked out much longer than others?"
MBIE joint head of MIQ Megan Main said overall the booking system had performed "extremely well and enables people to book spaces on a regular basis".
"There are consistently a significant number of people on the MIQ voucher site searching for an available date and the reality is there is finite space in MIQ.
"If a room becomes available on the site but is no longer there after a short period of time, this is because another person has just booked it - there can be hundreds of people competing for rooms at the same time in periods of high demand.
Main said the allocation system was designed to give everyone an equal opportunity for a room. "The system allows third parties to book on behalf of people who feel less confident with technology, including travel agents and family members.
"As with all aspects of our Covid-19 response, we are continuing to review our policies and procedures to ensure they remain fit for purpose, and keep our wider community safe. That includes exploring options including waitlisting and working on ways to release as many spaces as practicable at appropriately spaced-out intervals.
"It should be noted that even with a form of waiting list, there would still be insufficient spaces to fulfil the demand to come to New Zealand."
MBIE did not respond to Geddis' points that the system raises questions around discrimination under the Human Rights Act and Bill of Rights Act.
The most recent MIQ data, from yesterday, showed 1130 rooms were empty of the 4000 available rooms, over 25 per cent.
The number of MIQ rooms intentionally left empty as "contingency" increased from 400 to 900 at the opening of the transtasman bubble, while about 200 are unavailable because of hotel maintenance at the Grand Mercure and Grand Millennium.
The ministry said others were unavailable as it changed the way returnees were grouped, and moved to a "cohort" intake system.