Why do some Australians have accents similar to the English while others sound more like Crocodile Dundee?

I’m sure I’ve already answered this more fully elsewhere on Quora, but:

The distinction in Australian accents has historically been much more about class than region; the three distinctions identified 50 years ago were Cultivated Australian, General Australian, and Broad Australian.

Cultivated Australian was pretty much the same as British Received Pronunciation, except that its plural -es was formed as -əz instead of -ɪz.

Broad Australian is “Crocodile Dundee”. Or Steve Irwin.

General Australian is in the middle.

Cultivated Australian is much, much less prominent now than 50 years ago, when every doctor and lawyer on TV sounded like they’d just flown in from London. It’s fair to say it has been stigmatised.