Until a couple of weeks ago — before the coronavirus crisis — the biggest queues you would probably expect to see at supermarkets were at checkouts, as people lined up to leave.

Key points: Empty shelves are the result of distribution, not production, problems

Empty shelves are the result of distribution, not production, problems Retailers want emergency measures including curfew reforms to ensure better supply

Retailers want emergency measures including curfew reforms to ensure better supply Despite fears of looting, one retail expert says that is unlikely

Now, however, customers are queueing to get in, with lines stretching for hundreds of metres in some cases, as shoppers try to keep their distance from one another.

A surge in panic buying has induced "unprecedented" changes in consumer behaviour, and prompted a word of rebuke from the Prime Minister.

"I can't be more blunt about it. Stop it," Scott Morrison said on Wednesday.

"People are acting like jerks, drongos and bloody idiots," Western Australian Premier Mark McGowan said.

In WA, the police presence has been boosted in and around supermarkets, and police in South Australia are also "keeping an eye" on shopping centres.

"We're closely monitoring behaviour and activity around shopping centres. We have included that as part of our general patrol activity," Commissioner Grant Stevens said.

Fights have broken out in aisles, and the Australian Retailers Association said it was aware of at least two cases of knives being pulled.

Farming and retail authorities have repeatedly attempted to reassure the public that the nation is not running out of food — but many are asking, if that's the case, why are shelves still bare?

The answer involves consumer psychology, logistics and the way the nation's supply chains work.

Ignorance to blame for panic buying

If there's one thing authorities are absolutely agreed upon, it is that Australia is not running out of food.

The nation produces three times as much as it consumes, about two-thirds of which is currently exported.

Shoppers have queued for hours to gain access to supermarkets. ( ABC News: Emily Piesse )

According to Monash University supply chain expert Dayna Simpson, part of the reason for unabated panic buying is not simply fear, but ignorance.

"I think a lot of consumers — they worry that something won't be available, and so they don't really understand what goes [on] behind the shelf," Associate Professor Simpson said.

"We're very tied to convenience and being able to buy whatever we want, whenever we want."

The Australian Retailers Association said panic buying was driven more by perception than reality.

"If you can get stock on the shelf and if customers can walk in and a supermarket looks like it's full, they're highly unlikely to panic buy," executive director Russell Zimmerman said.

"They are looking at the shelves and saying 'oh my goodness, there must be a shortage' … if everybody stopped panic buying as of today, the shelves would fill up."

Supermarkets have imposed sales limits to gain better control of supply. ( ABC News: Emily Clark )

Mr Zimmerman said some consumers probably now had "six or seven or eight months' worth" of toilet rolls stockpiled in their home — far more than they needed in the short term.

"Most people would have in their pantry or cupboards at home approximately two weeks of supply without buying another thing," Mr Zimmerman said.

How can the supply chain keep up?

Food production is not the problem — instead, the issue of shortages has everything to do with distribution.

Supermarkets have grown in size over the decades, but are still limited in their amount of shelf space.

Mr Zimmerman said distribution centres (DCs) were currently chock-a-block with stock, but "the problem is getting [it] from the DCs into the stores".

Restrictions on deliveries from distribution centres are contributing to shortages, the retailers association said. ( ABC News: Michael Barnett )

He said council by-laws often imposed curfews on truck movements, restricting afterhours and late night deliveries to supermarkets.

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"What we're asking is for local councils to give approval for those trucks to deliver 24 hours a day," he said.

"There are restricted times in which the trucks can actually make those deliveries. If the truck can't [make the] delivery in time, they can't fill the shelves up."

Queensland has already flagged curfew reforms, while Coles has moved to employ 5,000 new staff to help cope with pressures in retail outlets.

While trading hours differ on a state-by-state basis, the South Australian Government has announced temporary deregulation to allow around-the-clock trading.

"We're not asking shops to stay open for 24 hours, we're just extending the window in which they can trade. Some may choose to close during the day because it's easier for them to restock," Premier Steven Marshall said.

Getting stock from warehouses into supermarkets is the main challenge, experts say. ( Supplied: Kimberly-Clark )

But the state's Road Transport Association said lack of shopping hours was not the problem.

"The delivery of product to replace the 30 to 40 per cent higher turnover in stock is struggling to keep up," executive director Steve Shearer said.

"Many councils, to keep the amenity nice in their suburbs, say you can't bring your trucks in here during these hours of the day."

Could looting become the next big worry?

One challenge for authorities has been battling outbreaks of violence.

The Australian Retailers Association is aware of at least two cases in suburban Sydney in which shoppers had threatened other shoppers with knives.

However, the SA Premier has been among those to caution against hysteria, warning that "fake news" was "unsettling people".

"There were [claims about] Army people on the corners of our streets — it's just preposterous, it's absolutely ludicrous and it's quite dangerous. It's frightening a lot of vulnerable people," he said.

However, he also said there had been "quite a lot of unacceptable behaviour from the public towards people working on the frontline in retail".

Mass looting broke out during the London riots in 2011. ( Reuters: Olivia Harris )

Former senior Coles employee and retail analyst George Panas is hoping such incidents will remain isolated.

He said appeals by the retail industry and by politicians for consumers to calm down would start to have an impact, and that mass looting was extremely unlikely.

"There'll be some heightened precautions obviously for the staff and their contact with customers," Mr Panas said.

"[But] I would be very surprised if any supermarkets looking at a large-scale looting type of possibility."