Hipkins said if Morrison was really so keen to see Australians travelling to New Zealand "I look forward to his removal of the requirement of Australians travelling to New Zealand to have an exit visa in order to do so."
Robertson said if more New Zealanders went to Australia than vice-versa, the tourism regions could end up losing out on the domestic market as well.
"This is a two-way street, and if Australians still require an exit visa, we could end up with a net loss to New Zealand," Robertson said.
"So what we would have to know is just how many Australians would be prepared to go through the rigmarole of that; in return, in terms of the net benefit to New Zealand, how many New Zealanders would go to Australia."
Hipkins listed other hold-ups to the transtasman bubble, including:
• Deciding on the circumstances that could result in a green-zone travel on either side of the Tasman being suspended and how to deal with travellers caught out by that suspension.
• The testing requirements on either side.
• Australia's "exit visa" restriction that prevents Australians travelling to New Zealand without a visa.
• State-by-state differences in decision-making in Australia.
• What would happen if bubbles were set up with other countries, and whether New Zealand would have any input into such decisions by Australia. Australia has proposed a bubble with Singapore.
• Contact tracing system interoperability to allow people on both sides of the Tasman to be found and notified of potential exposure.
New Zealand had originally hoped for a country-country agreement with Australia on the issue – but those negotiations stalled and each country was now making decisions on its own grounds, which Hipkins said had made resolving some of those issues difficult.
Hipkins noted only two Australian states were taking New Zealand travellers, and people from Auckland were still required to be tested on arrival and isolate until the results arrived.
He pointed to the risk of travellers being stranded if the boundaries were suddenly closed and quarantine requirements were reinstated, as happened in February.
"We have already seen examples of people's travel being disrupted and people being stranded as a result of Australia's suspension of the green zone.
"We've had flights on the tarmac at Auckland about to take off that have had to turn back when Australia, at very short notice, has suspended green zone travel."
Hipkins said while there had only been one case of Covid-19 originating from Australia this year, that was in the context of only a couple of hundred people arriving in New Zealand each day. The pre-Covid traffic was 8,000–12,000 people.