Because the more effective and proven strategy is to simply pay businesses and people to lockdown.
It has been effectively eliminated in both Australia and NZ this way. And the impact to the economy is significant but it's turning out to be far less severe than the rest of the world and their on/off again strategy.
This is anything but simple. Vast majority of businesses and people will not be supported if indefinite lockdown continues. The hidden costs of bankrolling an entire country for an indefinite period is much greater than the cost to deploy a persistent, scalable testing framework. The latter is also an investment into the future as this will not be the last pandemic.
Australia and NZ are not America. This is the same mistake Elon made when he suggested the US would have 0 new cases by this past April; the US is not China. The differences are actually so big that comparisons are dangerously misleading.
The problem in the US is that you cant pay people enough to change their minds about the politics. They would be, and many in fact are, millionaires and they would still refuse the test. Even if it meant jail time.
it's not indefinite - it's just long enough to cut down unknown transmission to a managable number for contact tracing to kick in. Then public health measures like masking up and distancing is effective enough afterwards.
Businesses cannot stand uncertainty - a on-off lockdown that they cannot predict is the worst, because they cannot make investment decisions with this sort of huge uncertainty.
The density of cities in australia and NZ are somewhat similar to european cities. The sparseness of Aus and NS are because their population is concentrated in cities, and there are large land masses.
If the US or UK wants to, they can certainly make the same sort of lockdown. There are costs to it, but the leadership being incompetent at actually leading, is a bigger roadblock over the cost.
The US could never do it because the federal government does not have that authority. They have lacked leadership, but they were also uniquely positioned for a world of hurt going into this.
The UK is doing about as well as similarly populous countries nearby. Which is to say, not well at all.
UK has a population of 60 million. Australia is 25 million. Both are a set of islands.
Not exactly an order of magnitude difference in population but yet there is a massive difference in the strategies and polices they've deployed. And now UK is a complete mess heading into winter and Australia has effective elimination.
I am in the part of Australia that didn't eliminate it well before winter. But with 112 days of lock-down _during_ winter we certainly had the numbers come down dramatically and have had twenty-three days so far of no new infections or deaths.
From tomorrow we no longer have to wear masks outside unless it gets crowded such that you cannot maintain physical distancing!
The UK is also next to Europe and a travel and business hub for the world. Australia is next to nothing important and has far less travel to and from the rest of the world.
China moved on from lockdowns over 6 months ago. They switched to citywide testing with 5:1 and then 10:1 pooled PCR tests in May and then recently switched to pooled rapid antigen testing. With the current testing methodology, they place one sample on a test strip, wait to see if there's a color change, and if not, they'll put a subsequent sample on. You can use a single antigen test for up to 10 people and patients get their results while at the testing site.
It has been effectively eliminated in both Australia and NZ this way. And the impact to the economy is significant but it's turning out to be far less severe than the rest of the world and their on/off again strategy.