There's no great mystery about the difference.
The ridiculous cost in Australia is due to the government's trade barrier, which says that importing Italian luxery cars is ok but bananas must be grown Australia.
It's an interesting debate from a sustainability perspective, but the inflexibility has meant the price is always going to be higher than it is in the US, and since a series of disasters has devastated the bananas industry in Aust, the remaining bananas are going for absurd amounts.
Given that it takes, in ideal conditions, 8-10 months for a newly planted banana crom to bear fruit, It strikes me as strange that the govt didn't just lift the trade barrier for 10 or 11 months. There are plenty of close Asian nations that would have been happy to ship over bananas. The price wouldn't have come down to US levels, but it would have dropped dramatically.
it might have something to do with the biosecurity treatment requirement.
But then again, it's probably the same as for other fruit, i.e. fumigation
Conventional: from $0.99/kg at the market to $2.99/kg at the supermarket
Organic Fair Trade: $3/kg at the wholesaler; $4.99/kg at the organic shop (they buy from the same wholesaler as me hehe)
59 cents per pound for Dole organic and 69 cents per pound Dole conventional at Dominicks in Illinois(not a typo).
A few weeks ago, I was paying about 40cents for conventional. Now I pay about 69 cents for conventional bananas here in the US. I am not sure what the reason for the spike is. The bananas are more expensive and many of them are rock hard green as well.
organic - $2,5/kg
conventional - $1,40/kg