Counterfeiting is unfortunately still a thing in Australia. A friend who runs a cafe makes his staff subtly attempt to tear any $50 note they take due to counterfeiting in the past.

They were caught out by scammers (or unknowing people with scammed notes) several times last year and the bank rejected the notes (and of course wouldn't hand them back)

Apparently the counterfeit notes are sometimes on a plastic too, but not sturdy enough to withstand a quick tear. I'm not sure how long that will hold true though.