Contesting Labor-held Lindsay, Fiona Scott told Four Corners that asylum-seekers were "a hot topic" out west, "because our traffic is overcrowded".

"Go sit on the M4, people see 50,000 people come in by boat - that's more than twice the population of Glenmore Park," she said, referring to a local suburb.

Her claim prompted progressive derision with social media memes depicting Indonesian fishing vessels clogging Parramatta Road. But Tony Abbott backed his candidate in and, just days later, so did voters. Scott was the new MP and Abbott was the new PM.

Did divisive rhetoric get Scott over the line? Hard to know. There was probably a stronger causality between her risible claim and her success, than had ever existed between traffic snarls on the M4 and boat arrivals.

It is no great revelation that in politics, xenophobia works - particularly during hard times. It got an unknown Pauline Hanson elected to the lower house in 1996 and has played some part in all of her elections to the Senate since.

John Howard triumphed in the 2001 "Tampa" election after famously declaring in a campaign speech in Launceston "... we will decide who comes to this country and the circumstances in which they come".

With his anti-Mexicans rhetoric, Donald Trump followed every authoritarian thug in history in by demonising a villainous "other" and turning bigotry, fear, and victimhood into a politically potent force. He rises again, unabashed.

These rhetorical forms work because simultaneously they validate grievances and offer a single explanation for them - foreigners. Fear of being "replaced", out-done, or even swamped, is deeply ingrained in the human psyche and politicians of a certain stripe can't resist tapping it.

Yet there can be a kernel of truth somewhere in these messages, too.

In Scott's case, the "truth" lay in the daily commuter experience that roads were failing to cope with traffic demand. In Howard's, it was the sensible proposition that self-respecting nations controlled entry.

Indeed, Howard argued that in managing their borders more forcefully, governments would be permitted to run larger humanitarian and skilled migration intakes.

However, dog whistling and racism in immigration/population policy has licensed a more negative effect.

Exaggeration of sometimes small policy differences between the major parties has served political interests and come at the direct expense of human beings deserving of protection. And it has impelled a bipartisan race to the bottom.

Witness Australia's infamous mandatory third-country detention which is so callous that even Trump was aghast when its cruelty was explained by Malcolm Turnbull.

Opposition Leader Peter Dutton's confused response to the budget exhibited these populist and theatrical overlays. In the broad, he insists the budget is irresponsible and inflationary.

Yet on its major spending - an expanded Single Parenting Payment, improved rental assistance, tripled doctor incentives for bulk billing, potentially all of the Jobseeker increases - he stands uncannily close to Labor. Even a hiked-up petroleum resource tax could be waved through.

Tellingly, Dutton gets more loquacious against immigration, but with little substantive difference.

"Over five years, net overseas migration will see our population increase by 1.5 million people," Dutton told Parliament in his address in reply.

Railing against a "the Big Australia approach", Dutton says it "will make the cost-of-living crisis and inflation worse".

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But he offers no meaningful separation beyond a Coalition record that, in fact, would have made Australia bigger, faster. Once again, a difference in emphasis is inflated to sound like a difference in substance.

"It's the biggest migration surge in our country's history and it's occurring amidst a housing rental crisis ... cities, towns and suburbs are already choked with congestion," (that word again).

"A Coalition government will sensibly manage migration ... in conjunction with proper infrastructure planning."

Forget two Glenmore Parks, the danger under Labor is of another Adelaide being added within five years.

It seems Dutton wants voters to be exercised - perhaps frightened - that Australia will reach a population of 27 million around this time next year, even though the last government's own pre-pandemic projections showed it being reached last year.

There is some irony that immigration is so easily weaponised when the economic forces driving policy tend, if anything, to defy political lines.

Employers are the most persuasive voice in government's ears, arguing for a generous, flexible migration intake. After years of closed borders, and with a tight labour market, businesses are desperate to use temporary migrant visa classes to fill job vacancies, expand, and meet orders. And they like a growing domestic market to sell into as well.

Unions on the other hand, believe employers and the state have too readily turned to importing cheap labour, thus driving down wages while side-stepping the onus to fund skills acquisition.

Dutton's question, "where are all of these people going to live" bespeaks a kernel of truth also. But his purpose seems more argumentative than inquisitive. By seeking to tie every problem to "Labor's" 'high' migrant intake - an under-supply in rentals, hospital beds, aged care, public transport, and childcare, plus high interest rates and inflation - he feeds nativist resentment. That's a lot to put at risk against a migrant intake that is no larger than the previous government's.

Politics - where facts are fungible, outsiders become villains, and broad agreement comes dressed as division.