[SulphurCrested]

The fallacy here is to assume either Adelaide or Melbourne are in the correct time zones with respect to the solar day.

Prior to 1895, Adelaide ran at solar time, GMT +9:14. When time zones were introduced, they went for GMT +9:00, but changed to GMT +9:30 after only 4 years. This probably reflected the reality that more people in SA live east of Adelaide than west of it.

Meanwhile, Sydney only had to put the clocks back 5 minutes to move from solar time to GMT +10:00, while Melbourne had to move the clocks forward 20 minutes to get into the same time zone as Sydney. (Both changes happened in February, 1895.) If we're going to have half-hour time zones, Melbourne is in the wrong one; it should be in the same zone that Adelaide currently uses.

So, in summary, by solar time Melbourne should be 20 minutes behind Sydney's current time zone and Adelaide 46 minutes. As there is a substantial population living on the NSW–Victoria border, not putting Melbourne at UTC+9:30 makes some sense. The same isn't true of SA's borders with Victoria and NSW. And so, we ended up with the current compromise, adopted in the era when railways and telegraphs became dominant.

[Someone]

> (Both changes happened in February, 1895.)

“Had” to Google whether that was a typo for 1985. It isn’t. https://en.wikipedia.org/wiki/Time_in_Australia#History: “The colonies enacted time zone legislation, which took effect in February 1895”

Also came across this tidbit as to why they have that half-hour difference (same URL):

“In May 1899, in a break with the common international practice of setting one-hour intervals between adjacent time zones, South Australia advanced Central Standard Time by thirty minutes after lobbying by businesses who wanted to be closer to Melbourne time and cricketers and footballers who wanted more daylight to practice in the evenings.”

https://en.wikipedia.org/wiki/Time_in_Australia#Anomalies also is a fun read, with

“The Indian Pacific train has its own time zone—a so-called "train time" when travelling between Kalgoorlie, Western Australia and Port Augusta, South Australia—which was at UTC plus 9:00 hours during November 2005 when DST was observed in the eastern and southern state”

[nirimda]

There's a lot of pressure, in every modern democracy, to have the timezone at least not behind the sun. It's so easy to sleep in, I guess, and so those of us stuck inside during working hours want at least some leisure time outside.

For people at the western edge of the timezone, it's fine, because they're advanced compared to the sun by design. For people at the eastern edge of a timezone, they're somewhat behind the sun by design. So in much of Europe and the US, countries/states/counties that should be in timezone X are in timezone X+1. Spain is a leading example of that, but even France should be in GMT. And everywhere that uses daylight savings is an example for at least half the year, some are double examples.

In effect, the error is the decision that timezones should be centred rather than east-aligned.