Canvassers out today on a frantic door-knock to get their vote out will often hear that heart-sinking refrain: “What’s the point? Voting makes no difference.” Or “I’m not political”, as if it were an optional hobby. Earnest volunteers may want to wring the necks of the apathetic, the clueless and the idle who are so hopelessly indifferent to the value of democracy.

But pause a moment and consider how right people are to be dubious. Whether they precisely know it or not, phlegmatic non-voters may intuit how useless most votes will be today. Under our grotesque voting system very few ballot papers will make a difference to the result.

In 2015 the Conservatives won with a seven-point lead, but so distorted is our electoral system that the Electoral Reform Society says if just 639 voters in only six Tory seats had switched their vote from Tory to Labour, there would have been a hung parliament. Just 639!

Another shocking figure: last time 74% of votes were wasted, in that they failed to make a difference to the outcome. Most people simply added to a stack of votes, useless once the winning number was reached, or else they voted for a losing candidate, so 22m votes were wasted.

Most seats are “safe”, some since the dawn of democracy: 103 Tory seats and 67 Labour seats have never changed hands since 1945, some not since Victorian times.

Abandoning first past the post for a proportional system could make everyone’s vote count. Grouping constituencies together in, say, six member seats, means most would be represented by at least one MP of their choice. As it is, what benefit-recipient on the sharp end of sanctions feels they will get a sympathetic hearing from their Tory MP? A rich family wrangling over inheritance tax with HMRC rightly or wrongly may feel they will get low priority from a Labour MP.

Today, an estimated 20% of voters will go to the polls wearing nose-pegs, forced to vote tactically for a party they don’t support, just to keep out the one they hate most. If allowed a second choice, they could vote with their hearts for their true beliefs and still have a back-stop second choice. New parties would have a chance: small parties will be crushed today.

Instead, sneaked into the Conservative manifesto is an extraordinary plan to spread the first-past-the-post system to mayoral, police and crime commissioners and even to the London assembly, removing second preferences, meaning less legitimacy for the winner. If there is any such move, it’s time to demand a constitutional convention to examine the whole tottering structure, from the House of Lords to local government powers.

Look how money contaminates politics, likely to emerge as even more monstrous this election: latest Electoral Commission figures in this campaign show Tories raking in 10 times more large donations (those of more than £7,500) than Labour. Money matters, and voters know it, 77% saying donors have too much power. A majority – 57% – for the first time now support state funding of politics, to stop business seeking favours and trade union barons leaning on Labour. (Unite’s Len McCluskey commands vital donations, though himself was elected on a turnout of just over 12%). Apart from Luxembourg, Britain has least state funding of politics among 15 European countries, just 18%; the rest has to be raised from donors.

The multiple dysfunctions of our corrupted democracy make it hard to argue on the doorstep that politics is noble

A constitutional convention would surely make registering and voting easier, instead of leaving it to the self-interest of governments. Yet again 15% are not registered today – the young, renters and ethnic minority people mostly. Of course people should vote electronically: many countries facilitate this, and if it’s safe enough for banking, it’s safe for voting. Time to give 16-year-olds the vote: make it compulsory for first-timers, so they get the habit. How good it would be to see candidates beg for votes in sixth-form colleges as well as retirement homes, to shift funding fairly between generations.

The multiple dysfunctions of our corrupted democracy make it hard to argue on the doorstep that politics is noble – though I respect most politicians for taking up what is for many a thankless task, with very few, brief moments when any feel they have the power to make something happen.

Don’t hold your breath for change, however blindingly obvious the need. There will be no constitutional convention unless some gigantic scandal forces it, or until enough people are indignant enough. Tories see reform as a leftist plot, a progressive alliance conspiracy against Toryism: look how they sabotaged the alternative vote referendum in 2011. Until Ed Miliband, Labour resisted reform just as fiercely. The language and rhetoric of reformers needs to change: until they persuade Tories that this is about democratic fairness, not an anti-Tory fix, nothing will happen any time soon.