Two out of every five voters in Indi and one in every five in Farrer took advantage of a pre-poll vote at the May 19 federal election.

Charles Sturt University associate professor in political science Dominic O'Sullivan said there would be "enormous voter backlash" for restricting access to pre-poll centres.

University of NSW law dean Professor George Williams told Parliament's electoral matters committee that voters should have to show evidence they were unable to get to a booth on election day

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"The system has become so permissive that people can vote early even when they have no reasonable basis for doing so," he said.

"An exceptional method of voting has become the norm for vast numbers of Australians."

Professor O'Sullivan said he agreed with Professor Williams that many early voters were making a choice based on "incomplete information".

"Early voters can't get access to the costings (for each party's policies) but they can get access to other forms of information," Professor O'Sullivan said.

"However, they don't get to base their vote on any new policies that are announced.

"In some respects parties are mitigating that by announcing polices early and you now don't get much stuff announced in the final week of campaigning.

"The counter-argument is that if people decide that they have enough information to make a voting decision, perhaps that is up to them to decide."

Professor O'Sullivan said there could be a link between a seat being a safe bet for a particular party and rate of early voting.

"You do have people who declare that they would never vote for a certain party no matter what because their polices are so far removed from that they could support," he said.

More than 40 per cent of voters in Indi cast their votes at pre-poll centres before booths opened for the May 18 federal election.

Two days before the poll, Australian Electoral Commission data revealed that 16,710 votes were cast. By the same Thursday, 13,113 people had voted in Albury compared with just under 10,000 at the 2016 election.