It might help though move acceptable borders from state border to "hotspot" borders. Even if the hotspot is still "Greater City" area. I think the big problem with hotspots is that state governments, rightly, don't trust people to tell them the truth (about being in a hotspot) so they just ban the whole state. Which is quite ridiculous - Broken Hill residents (to take an extreme example) live further from the northern beaches of Sydney than 90% of Victorians and almost 75% of Queenslanders.
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, and probably have more exposure to an Adelaide outbreak than a Sydney one, although granted there probably is exposure via health workers coming from Sydney.