Lockdowns ain't lockdowns.
There are weak lockdowns, where people are told not to do A, B, and C, but are still asked (or permitted) to do X, Y and Z.
Then there are draconian lockdowns, where people are told not to leave their homes other than for immediately life sustaining essentials, such as obtaining food or medical needs.
Orthogonal to these lockdown rulesets, however, is compliance. A lockdown is a set of rules; But its effectiveness is a combination of how restrictive the rules are and how diligently they are followed.
Trying to determine how effective lockdowns are by looking only at what the rules were is futile; The important question is 'how effectively did people actually isolate from one another?'.
Hence the apparent anomaly in Australia, where Melbourne had stricter rules than Sydney, but less success in containing the disease.
The difference was the demographic in which the majority of cases occurred.
Sydney cases tended to be amongst 'white collar' workers, who could telework, or who had permanent and/or salaried jobs such that obeying the rules and staying home was a minor burden.
Melbourne cases were far more prevalent amongst the 'blue collar' workforce, many of them in casual employment, for whom working from home is not possible, and to whom the loss of a day's work implies the loss of a day's pay.
Tell these latter people that they must stay home, and they will respond by asking 'who is paying?'. If there's no easy, quick, and dependable system in place to compensate them for loss of wages, they will go to work regardless of the rules.
The big outbreak in Brisbane that triggered a severe lockdown was centred on Indooroopilly, an affluent suburb with lots of white collar workers. Many of those directly affected were physicians and surgeons; The lockdown had a significant impact on our hospitals due to the large numbers of senior staff who were in quarantine. But compliance was very high - these were people who could easily afford to miss a few weeks of income, and who could be expected to understand the epidemiological reasoning behind being told to do so.
The Brisbane lockdowns worked extremely well. Sydney's worked notably less well. Melbourne never really got on top of things, not because 'lockdowns don't work', but because 'lockdowns need compliance to work', and 'lockdowns need financial safety nets to achieve compliance amongst blue collar workers'.
Lockdowns don't work in the USA, because the USA is utterly pathetic at protecting its people against poverty.
If you want people to stay at home, you need to pay people to stay at home. Lockdowns don't work if they're all stick and no carrot.
