My understanding, from how people use it here is that irony is a situation which is a contrast between the expected/intended and actual outcome.

It’s ironic when a fire station burns down

This definition is truly upsetting: https://www.merriam-webster.com/dictionary/irony

Americans, no. Bad Americans.

This definition is correct (until we come up with a good substitute, FFS America): https://en.wikipedia.org/wiki/Irony

Glad Wikipedia agrees with me on this one haha We’ll at least the introductory definition.

Edit: to answer your question. I dunno. I just think this form of “ironic” just didn’t take off in Australia.

Mostly because we already have words for what Americans use it for. And don’t have words to replace irony.

¯\_(ツ)_/¯