If Britain’s politicians believed in defending democracy, there would not be an election on Thursday. Our leaders would have held back until laws controlling propaganda and foreign subversion were in place. They haven’t waited, because they don’t want to protect the integrity of the ballot. With wolfish smiles, they have welcomed the opportunities for spreading fake news that the web has brought them.

As the paper was going to press, the final online advertising blitz had begun. Full Fact, the campaign group that fights the necessary battle to keep public life clean, was monitoring online adverts from the Conservatives saying that the cost of a Corbyn government will be £1.2tn – a figure based on assumptions that are dubious to the point of fatuity – and promising to recruit 50,000 new nurses – a straight lie. Labour was claiming that a Tory trade deal with the US would increase NHS costs by £500m a week – a statement that is as good as a lie, as there is no trade deal to cost – and merrily chirruping that 95% of people won’t have to pay more tax to fund its dazzling spending spree, which, as the Institute of Fiscal Studies points out, isn’t true either.

The official explanation for waiting until the final days of campaigning to “blitz” the wretched public is that millions of voters have not made up their minds – and given the foul choice of Boris Johnson or Jeremy Corbyn, who can blame them? Now is the moment to convince the waverers and seal the deal. Perhaps, but do not forget that the parties know that they can push out any old lie now. The election will be over by the time opponents and journalists have exposed it. Writing of how he helped tear apart the country he professes to love in 2016, Dominic Cummings said that his Vote Leave campaign “served about one billion targeted digital adverts, mostly via Facebook and strongly weighted to the period around postal voting and the last 10 days of the campaign”. Victory is all, and once it has been gained you can dismiss everyone who complains as conspiracy theorists and bad losers.

Without prompting from Vladimir Putin, Donald Trump or Xi Jinping, both major parties want to spread big lies

It’s a line of abuse we should have learned to reject by now. No one can prove that Russian subversion of the 2016 US presidential election guaranteed Trump’s victory or that Johnson and Michael Gove’s dirty tricks secured Brexit. But you can say with confidence that a once admirable feature of British public life has been surrendered without a fight.

Tight election laws limited the scope for corruption. The bribing of politicians is so institutionalised in the US it’s not even called by its real name. The need to fund TV adverts for primaries and elections has entrenched the money power of corporations and special interest groups so deeply it seems nothing can shift them. In Britain, the Communications Act 2003 prohibits “political advertisements” from being broadcast on TV or radio. And that worked well enough in its rough way as a control on politicians who would do anything to get the money they needed to win.

Now political ads can be broadcast online without any legal control. They are exempt from the Advertising Standards Agency’s rules and their accuracy is not regulated by the Electoral Commission. Instead, Labour and the Conservatives have happily outsourced the regulation of elections to tech conglomerates that care nothing for democracy in general and British democracy in particular.

The ads from the main parties have been flowing fast and they are about to come at citizens in a torrent. But to concentrate on them is to miss the 67 “non-party groups” registered with the Electoral Commission and give every appearance of being front organisations. One looks as if it is promoting the Green party, not because it supports the Greens but because it wants to split the anti-Tory vote. In every case there is no legal requirement for the advertisers to tell the viewers who they are and where the money is coming from. The Electoral Commission has been calling for years, to no avail, for the government “to work with us in making it clear to voters who is paying to influence them online”. The chairman of the Commons inquiry into fake news said in June that there should not be another election until the government introduced “emergency legislation” to update electoral law. And yet here we are.

The inaction is not the result of some Kremlin plot. Without prompting from Vladimir Putin, Donald Trump or Xi Jinping, both major parties want to spread big lies: Labour that it can spend like a drunken sailor while only taxing the hated rich; the Tories that they can “get Brexit done” – just like that – without inflicting grave damage on the economy and trapping us in years of bitter, pointless negotiations. They might have reformed election law in the last parliament. But why would they, when restrictions would work against the mendacious election campaigns they were gagging to run?

The late and much missed Clive James wrote: “For years now – all my life, in fact – there’s been something building up in western liberal democracy that should have been foreseeable, but perhaps was too obvious. There will be a penalty paid for prosperity and stability, and the penalty is that the young will forget. Liberal democracy in the west can die of itself. It doesn’t need an enemy, it can create its own enemies.” Nowhere is that more true of James’s adopted British home. You don’t need a Putin to subvert British democracy when it will happily subvert itself. The democratic politicians charged with protecting the integrity of the democratic process refuse to act because they fear that expanding the rule of law will force them to be honest.

There will be a bill to be paid whoever wins on Thursday. Itemised on it will be disillusionment, justified cynicism and a collapse in what little faith remains in the capacity of British institutions to reform themselves.

• Nick Cohen is an Observer columnist