The posters are going out under Malcolm Turnbull’s signature “I guarantee Medicare stays”. The government is clearly alarmed that Bill Shorten’s Medicare scare campaign could take hold.

But what, in the public mind, is the currency of a “guarantee”? We’ve had so many of them. No cuts to all sorts of things, from Tony Abbott. No carbon tax, from Julia Gillard. Never ever a GST, from John Howard.

This is not to suggest that a re-elected Turnbull government would seek to “privatise” Medicare – that would be an act of madness. The most it would do probably would be nibble at its edges, as it has attempted.

Rather, the point is that in the minds of many voters, a politician’s “guarantee” these days is worth little more than a horse laugh.

And it is indeed a laughing matter to have Treasurer Scott Morrison complaining about Labor’s scare campaign, condemning it as a big fat lie.

“We are not making any changes to Medicare,” Morrison said on Monday, in a quote that is worth stowing away for a (presumed) second-term Morrison treasurership, when he is looking for the budget savings he says we need. Morrison is the grand master of the scare campaign – remember his claim about Labor’s alleged A$67 billion black hole?

In an attempt to head off the Labor scare, Turnbull has ditched the government’s consideration of outsourcing the Medicare payments system. But Labor just says: don’t believe him. Health spokeswoman Catherine King on Monday could simply reference the past: “Malcolm Turnbull’s promise to ‘never, ever’ privatise Medicare is as believable as Tony Abbott’s promise before the last election of ‘no cuts the health’”.

Every time a leader spectacularly betrays trust, he or she leaves a landmine for their successors. The one left by Abbott when he pledged “no cuts to education, no cuts to health, no change to pensions, no change to the GST, and no cuts to the ABC or SBS” – and then trashed so much of that in the 2014 budget – was especially lethal. Howard did redeem himself, after his “never, ever” promise, by putting his planned GST to an election.

We can’t rid elections of scare campaigns, and sometimes they are legitimate. But often they are not, or are totally exaggerated, and in those circumstances they further weaken the low public trust in the politicians and the system.

They also undermine a good policy process. Turnbull’s removal of outsourcing Medicare’s back office from the agenda has been driven purely by political considerations. But shouldn’t we actually be discussing whether that policy option would save money, increase efficiency and make no difference to the principles underpinning Medicare?

Maybe it would be found wanting on all fronts, or perhaps it would be a desirable way of doing things. The point is, we haven’t had proper consideration because the politics took over.

The debate about health policy generally has been disappointing in this campaign, especially given that it is at the centre of Labor’s pitch to voters.

The ALP has promised not to do various things the Coalition has done or sought to do. It would end the freeze on the Medicare rebate (extended in the budget), not increase the cost of prescriptions, not take away the bulk-billing incentive for pathology and diagnostic imaging. It would put more money into the hospital system than the government has announced.

But Labor’s hospitals policy had little detail. It has a lot of measures out there but the election has been short on serious consideration of how Medicare should be improved to meet contemporary needs and ways to have a more efficiently operating hospital system.

There has not been the usual National Press Club (NPC) health debate between the minister and shadow minister.

Debates have stretched back a long way: in 2013 Tanya Plibersek faced off against Peter Dutton; in 2010 it was Nicola Roxon versus Dutton; in 2007 Abbott versus Roxon; in 2004 Abbott versus Gillard; in 2001 Michael Wooldridge versus Jenny Macklin.

Maurice Reilly, the chief executive of the NPC, said the club had contacted both parties. Labor had accepted; the Liberals “haven’t offered a date”.

And they are not likely to either, and can now use the excuse there is virtually no time.

Health Minister Sussan Ley had a glitch when she said she wanted to end the Medicare rebate freeze but “Finance and Treasury aren’t allowing me to do it just yet”.

The last thing Liberal campaign HQ wants is a vulnerable minister to be exposed to a serious grilling on one of the hottest topics of the late stage of this campaign.