Every democracy’s electoral system gets tested by old-style scheming. Perpetrators might deploy communications as simple as signs on buses or as sophisticated as data-driven algorithms that seem to be detected only after they have spread their targeted deceptions.

Traditional media, being both journalism providers and commercial platforms for political advertising, have always been players in elections – knowingly, to varying extents. New media, especially Facebook, Google and Twitter, are increasingly important as hosts, enablers and beneficiaries of political messaging, paid and unpaid.

We are used to thinking of adverts as fixed things that appear in the same way to many people. This idea is out of date

For old and new media, conflicts of interest are inherent in the mixed roles. But they are not quite as severe as the conflicts the major political parties face. For electoral combat, the parties need maximum room to move, fudge, persuade, to strive for power accompanied by the legitimacy that electoral victory can confer. Yet, as legislators, they have a duty to the public to maintain a system capable of delivering free and fair elections.

A growing number of credible voices are asking whether electoral systems are any longer fit for purpose, and so far there appears to be little appetite among most of the strongest media and political players for the delicate inquiry and reform that technology and experience seem to demand if election outcomes are to retain public confidence.

The latest analysis, by the UK fact-checking charity Full Fact, is clear-eyed about the importance of not grasping at excessive regulation at the cost of freedom of expression. In lean prose, its new paper, Tackling Misinformation in an Open Society, summarises the weaknesses of both the law and oversight of the UK electoral framework. They are vulnerabilities of many electoral systems (not just the UK’s) that were built for a passing age.

“When an election stops being a shared experience, democracy stops working … We are used to thinking of adverts as fixed things that appear in the same way to many people. This idea is out of date,” says Full Fact. “The combination of media buying by computers, and adverts being created and personalised by computers, mean that online advertising is not a shared experience any more.”

The paper mentions a leaked Facebook study that found that Donald Trump’s presidential election campaign ran 5.9m different versions of ads, rapidly testing them and spreading those that generated the most Facebook engagement. The Hillary Clinton campaign ran 66,000 different kinds of ads.

“Policymakers need to account for the shift towards dynamic content advertising, in which customised adverts are assembled based on rules according to what is known about a viewer from their browsing history on a site or network of sites. Adverts could be personalised based on what the advertiser knows about you; what the advertising network such as Facebook, Google or Amazon knows about you; or based on data from third parties such as Experian or MasterCard. Personalised advertising will only become more sophisticated as technology and access to data develop.”

Media organisations, like their clients, are expert in this new digital ecosystem because their commercial selves depend partly on it. They could do more to explain to audiences – as voters, not consumers – its implications for elections in democracies. They could agitate more for much-needed action in the public interest by naturally reluctant political parties.

Drily observing that humans cannot evaluate 5.9m unique variations of ads, Full Fact concludes that if electoral advertising transparency is to be held accountable it must: be provided in real time; fully disclose its content, targeting, reach and spend; and be in a form that machines can read.

• Paul Chadwick is the Guardian’s readers’ editor