How does that prove that you only voted once? If I know someone's name and address (and by extension their electorate) I can rock up and vote as as many as I want.
Then you go to jail (penalty is 6 months for impersonating a person and voting on their behalf.) It's not like polling locations don't have cameras.
(A few people voting more than once is unlikely to change the results of an election. If enough fraud is detected to impact the results, they'll run a new election.)
> It's not like polling locations don't have cameras.
Given they are usually random primary schools and churches... do they have cameras?
I think the bigger deterrent is just the risk of claiming to be someone who already got ticked off at the same booth, which would immediately raise suspicions.
(A few people voting more than once is unlikely to change the results of an election. If enough fraud is detected to impact the results, they'll run a new election.)