Australian English does not place a period after titles that would end with the same letter as it would be unabbreviated.
e.g.
Mister = "Mr." in U.S. English and "Mr" in Australian English.
Reverend = "Rev." in both U.S. and Australian English.
The period *ahem* full stop in "Mr" is omitted in British English too—makes sense that it would carry over to Australian English.
I didn't know the rule in AmE was to specifically use this dot. I grew up with BrE and I just thought that anyone using "Mr." was just not aware of this obscure rule about final letters (plenty of people in the UK use "Mr." too).
