Respectfully - this is I think the point that
@Julian Seers-Martin made (and which I hadn't understood). I don't think the argument is against the ANZ strategy per se, just whether it could have been replicated by the UK.
Even setting aside the level to which Australia and New Zealand may rely less on imports of food and other necessities, everything that arrives in those countries arrives by ship or by plane, and can be removed from the vessel without any interaction with the people who brought it over.
On mud island, however, freight mostly comes from the continent, and mostly comes by truck - 10,000 trucks per day - and the driver stays with the truck. Therefore, in order to deliver the same level of isolation as those countries, we would have had to create some kind of new logistical system which avoided having the drivers coming into the country, and avoided any close contact between those drivers and people in the country already.
I have no idea whether anyone even went down the path of trying to plan such an endeavour, but instinctively (to me at least) it sounds orders of magnitude more complex than, say, the Berlin airlift.
That's not to argue, at all, that the borders shouldn't have been shut down earlier, or that lots of other things shouldn't have been done differently - but certainly the simple question "Australia and New Zealand did it - why can't we" seems to have a simpler answer than I realised...