In reply to WyeValleyClimber:
I don't think it's modern, it's more likely to be an older form of language that went to the 'colonies' and then developed it's own way. It's a very common usage in Ulster Scots, which might be one reason for it's usage prevalence in Aus/NZ.
Why you think younger people are using it more and more, i'm not sure - maybe they are, maybe it's confirmation bias. It's certainly a form of words I use a lot (i'm from the south of scotland) and always have done, except when corrected by the 'old skool' teachers, who tried to iron any hint of an accent/language form/alternative grammar out of us, with mixed success. Different dialects are more than just different vocab - the grammar and accepted forms of usage are different, not just lazy forms of 'proper' english. I'm in my mid-30s, but 'can i get' is way more common with the older generation from where I grew up.
I"m not sure if I used 'uni' when i was at uni nearly 20 years ago. Maybe I did. I certainly use it now.