That's because they've already cast their vote - in some cases as many as 19 days ago.

Across the three Illawarra and South Coast electorates a staggering number of voters have visited a pre-poll centre since they opened on April 29.

In Gilmore, as of Thursday a whopping 42,349 people have already cast their vote - that's 34 per cent of all registered voters in the electorate.

As many as 35,025 people in the Whitlam electorate have better things to do on Saturday than queue up to vote.

That pre-poll figure represents 29 per cent of the electorate.

By comparison, Cunningham voters seem happy to wait until Saturday - 22 per cent or 25,522 people have already voted there.

Whitlam MP Stephen Jones said the high number of pre-poll votes in his electorate was "unprecedented".

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"It's been getting larger and larger for each of the last three elections as the electoral commission has had a more permissive approach as to whether you can or can't pre-poll," Mr Jones said.

"It was originally introduced for people who were working or who weren't going to be there on polling day but now the electoral commission basically takes the view that anyone who wants to vote early can."

Election campaigns have long been structured around the last two weeks before polling day, when people tend to start paying attention.

However, Mr Jones said campaigns have had to change as more and more people vote early.

"Normally, for example, you would have a couple of big initiatives held back for the last week because nobody was paying attention until then," he said.

"But if a third of the population has voted by then you've got to change your mind, you've got to do things differently."

There are laws around who is eligible to pre-poll, which include those who will be more than eight kilometres from a polling place, those who can't leave their workplace or who will be out of their electorate.

However, people do not have to prove their eligibility, they just need to state they are eligible.

Mr Jones said it might be about time someone took a close look at the increase in pre-polling.

"One thing is that people vote but I do think after the election that we have a discussion about this," he said.

"There was never a public debate in this country as to whether we have one polling day or 15 of them, it just happened."