Australia has been letting in anyone who has been in NZ for the prior 14 days since September last year. New Zealand has not reciprocated until this week. I think you'd find that the tolerance for the virus in the community is highest in New South Wales where it had been around almost all of last year and the start of this year (the reason NZ has not had a bubble with AU) and lowest in Western Australia, Queensland and New Zealand where any outbreak is followed by a lockdown and there is zero tolerance of any transmission.