Not quite so difficult if you live on an island.
One, we had 9mil visitors in 2018, so it's not an island nobody ever visited in the here-be-dragons section of the map.
Two, we still have 3K people flying into Sydney per week, so it's not a completely isolated place. We're even allowing visitors from NZ without requiring quarantine.
Three, we have higher urbanization than the US or UK, so most of the population is living in a few cities. We're not all spread out 5 miles away from each other. So it's a comparable problem to that faced by other countries in that regard.
Four, even as an island, Covid still got here. So it could still spread once here. but we never lost control of the spread(Semantics, I know, you could argue that Melbourne lost control and that's why there was a lockdown). That's due to the steps taken to prevent the spread, but this _never really gets discussed_.
Five, and this is the important thing I think everybody overlooks, NSW has had cases in the community, but we've NOT had exponential growth and a lockdown. We're handling the problem in NSW without lockdowns, which is what a lot of anti-lockdown protesters think should be done. But every time Australia is mentioned, nobody discusses how this is accomplished, how it could be better, what others could learn from it. No, it's only ever "Hurr, Durr, They're an Island".
So, to actually discuss how Australia does it...
I personally think that the contact tracing in NSW is second to none. They take a lot of steps to be able to contact everyone who comes in contact with a positive case as quickly as possible, and this means that each positive can only really infect one or two people before they're isolating. A lot of people are told to isolate because they came in contact, then they never pass on the covid.
They also test waste water so they know if there's undetected covid in a region, like Bathurst, then ask people in that region to get tested. It's better than "wait until cases come forward".
Mainland USA only has land borders with Canada and Mexico, right? Do you believe that if those borders were impermeable that they'd have COVID beaten? And the only reason the outbreak there is so large is due to cases sneaking in from Mexico and Canada every day? In reality, the vast vast majority of USA's COVID cases came from the exact same place as the majority of Australia's COVID cases - people flying in, and community transmission.
Yes, Australia has had a few advantages when fighting COVID. But hand-waving Australia's success away as "it's an island!" just serves to ignore the lessons that could be learned from Australia's response.
I suspect most countries who would take a 4-month lockdown would be in a very good condition.
The place where being an island helps tremendously is with avoiding re-introduction.
It is an island is a silly response, we didn't shut borders before COVID got in so it isn't like us being an island is hugely impactful. Australia has done a really good job of handling community spread within Australia.
What proportion of the COVID cases around the world do you think are happening because of people from the outside a country visiting vs community spread to think the island thing is especially relevant?
An island of people who for the overwhelming majority stayed inside, social distanced and had a positive attitude to removing the virus. But we weren't without our mistakes, Victoria allowing a black lives matter rally really shot themselves in the foot with eradicating the virus. They would've been in a much better state earlier had they not had that rally, given there was a large number of communication transmission following.
If you think there's a "clear" relation it makes me think you're not following Australia at all.
It's obvious that if you're an island that is far from the rest of the world by a few hours by plane that it's easier to isolate. And that's doubly true for New Zealand.
Oz better hope that that a good vaccine emerges: otherwise they're not going to like "round one" of Covid, much less "round two" which many countries are going through now. Ozzies have no immunity unlike the rest of the world.