NZ and Oz have natural advantages - which we ran hard with when the pandemic hit (and then again when community transmission was detected). Why on earth wouldn’t we?!
The UK doesn’t have some of those advantages, and so the response from leadership, at least in the early days, was almost ‘why even bother trying?’ The arrival of spring and summer almost seemed to lull people into a false sense of security.
The virus was inside both NZ and Oz, and it was spreading. Without the measures we took, it would have run rampant through our communities, killing tens of 1000s, just like it has elsewhere.
Yes, parts of our countries might be empty, but the cities and suburbs are populated enough for the virus to sweep through. We know that, because it was doing just that.
In NZ, the biggest cluster/spreader event was a wedding (which killed the groom’s father, incidentally).
COVID-19 is highly contagious. Our less densely populated countries would’ve made very little difference, if we hadn’t taken the measures we did.