Yeah, they have voluntary voting in the USA and every trick in the book is deployed to PREVENT people voting.

You would be lucky to get a 25% turnout if voting was voluntary.
Apathetic, lazy Aussies would rather be at the beach.
Sad but you all know it is true.

No government could ever claim a "mandate" on only 25% of the vote.

Tony,

Voting is a right not a duty in nearly every country. If the government needs to conscript people to vote, it needs more than just feel good to justify it.

People have the right not to give a crap.

Shadow,

In Australia they can exercise that right by writing 'crap' on the ballot paper.

What about their right not to go to the polling station?

There was a brief period in NSW when voting was not compulsory in local government elections, turnout was less than 30% and with proportional representation, a very few votes could get one elected. They soon returned to a compulsory system.
Today many people vote pre-poll which once upon a time was difficult to do, you had to have a good reason, but now its rather easy, virtually just front up no questions asked. I think we need to move the whole system into the 21st century, and I don't mean stop electing dinosaur people, streamline the system to include on line voting etc.