Western Australia is also a state and we've regularly locked down all travel from other Australian states when they have community outbreaks. We have a COVID death rate lower than New Zealand and, like NZ, have lived essentially normally throughout COVID despite the travel restrictions.

Currently you can only come here from NSW with express permission and then you have to quarantine at your own expense for 2 weeks. Quarantine requirements kick-in whenever there's a community outbreak in other states/territories and the restrictions ramp up as case numbers grow.

It is easy for Western Australia and Tasmania to isolate because the former has a vast desert between here and the east coast and the latter is an island without an international airport (probably one of the safer spots on Earth). There's no physical reason Hawaii and Alaska couldn't have done the same, but it's probably not politically or socially acceptable.