The patchwork of inconsistent COVID restrictions across Australia serves a purpose, albeit an accidental one.

Different conditions with boundaries between them tell us how effective infection controls are because we can test on both sides of the boundary. /1

Different regions have different levels of strictness, with different boundary conditions.

Obviously metropolitan Melbourne is the strictest. The rest of Victoria is less strict. Is the boundary between them porous? /2

By jingo it is, because Melbourne's contagion is spreading to the regions. That's actionable intelligence for the rest of the nation, in judging how it should respond to a Melbourne-style outbreak (e.g., Go to L4, with a L3 ring around it) /3

Is Victoria's L3 effective? Hmm, potentially. The Queensland and SA cases after Melbourne went to L3 suggest probably not. So that informs other States about the stance they need to take too. /4

What about NSW? Is that a risk to the other States? In theory it perhaps is, but the fact that there are no controls whatsoever between NSW and ACT, and ACT doesn't have any NSW-originating cases, suggests the risk is probably minimal. /5

So that can lend a degree of confidence to the other States: The degree to which they need to worry about NSW is lower than it would be if NSW community transmission was significant enough to be bleeding in to Canberra. /6

... and if that changes, the ACT will know how to respond (e.g, a Queensland-style border to protect itself from a hypothetical more significant NSW breakout) /7

In a couple of weeks, NSW will have dealt with the transmission Victoria inflicted on it, and will be back to nil observable cases outside hotel quarantine. If that includes border communities, that means the border permit system is effective. That's useful knowledge too. /8

Summary: If the whole country, or even a whole state, is at the same restriction level, the signals public health workers can get from COVID-19 propagation are necessarily coarser and less informative than they are when there are lots of different restrictions. /9

So maybe don't complain about how complex and inconsistent the landscape is. The only bit of the complexity that matters to you is, "Can I do the thing I want to do tomorrow?" and that's a yes or no answer. Pretty simple, and pearl-clutching about the rest of it is silly. /fin