My son has just been given a new toy car. It’s small, blue and remarkably cute-looking for something that threatens one day to cost a lot of people their jobs. For what’s unusual about this car is that it wasn’t made in a distant Chinese factory before being shipped back to a warehouse here, then trucked to a shop, or dumped on a doorstep by an overworked Amazon driver with no time to ring the doorbell.

This one came straight off a 3D printer, one of those faintly space age-sounding gizmos that works a bit like a normal printer except that you load it with plastic fibres instead of paper, and then programme it to “print” a solid object according to your preferred design.

It’s slow and expensive now, which is why the car my son was given isn’t really a toy but a marketing gimmick. But it will get quicker and cheaper, maybe cheap enough that 3D printers will before long be as common (at least in better-off homes) as espresso machines are now. And when that happens, if you need to buy something new, smallish and plastic – a toy, a kitchen gadget, a spare part for something boring – you won’t have to go out and buy it. Just pay via an app for the appropriate design to be downloaded to your home printer, which could churn it out in the comfort of your kitchen.

The virtues of no longer manufacturing and moving stuff great distances are obvious: not just convenience, but potentially huge environmental benefits. We’d need fewer polluting factories, fewer planes and ships and lorries clogging up the planet, and if we could figure out ways to recycle at home – melting down old plastic tat and using this raw material for printing out new plastic tat – infinitely less landfill.

But the disadvantages are clear, too: vastly fewer jobs in factories, transport, warehousing and what’s left of retail, as what Amazon did to the high street eventually starts happening to middlemen like Amazon, too. And while there would be winners as well as losers, the losses would be dangerously unevenly spread.

Women have been hardest hit by job losses in retail, but it’s men who would fare worse in this scenario. Consultancy firm PwC reckons 35% of men’s jobs are at high risk of automation versus only 26% of women’s, partly because women are more likely to work in human-facing, socially skilled professions such as teaching, which are harder for robots to master.

‘New jobs created by the “fourth industrial revolution” more likely to cluster in shiny Shoreditch than in the fading post-industrial towns where jobs would be lost.’ Photograph: Alamy Stock Photo

The new jobs created by what is sometimes described as a fourth industrial revolution, meanwhile, are more likely to cluster in shiny Shoreditch than in the fading post-industrial towns where jobs would be lost. It’s not just a bomb ticking under employment and welfare policy, education and a system of taxation that currently relies heavily on real living humans having jobs on which to pay tax in the first place. It’s also a recipe for resentment, division and smouldering social unrest.

All of which explains why Labour sidled closer this week to the idea of a robot tax – or, strictly speaking, taxing profits generated by automation, with the money perhaps used to retrain those whose working lives are disappearing or to forcibly spread the proceeds of new growth. True, Jeremy Corbyn promptly sidled away again in his keynote speech, delivering a somewhat watered-down version of what was briefed in advance. But if Labour is as yet maddeningly vague on the detail, it has at least put itself on the popular side of a big coming argument. The Tories have a lot of ground to make up when they meet in Manchester next week, and yesterday’s lecture from Theresa May about capitalism still being the engine of prosperity is an underwhelming start.

Paradoxically, the hardest ideas for politicians to articulate convincingly can be the ones so obvious they’ve assumed it would always be taken as read. But accepted wisdom dissolves amazingly fast once enough people simply stop accepting that, say, Britain’s place is obviously in Europe, or that neither democracy nor capitalism is perfect but all the alternatives are worse. The biggest mistake in contemporary politics is failing to renew popular consent to things that seem obvious, but are no longer nearly so obvious to voters.

The near-hysteria with which some Tories reacted to the mildest of interventions in Uber suggests that they still don’t understand how the climate has changed. Hostility towards tech moguls is building just as it once did towards bankers, and for much the same reasons: a wealthy elite threatening other people’s job security will eventually trigger a backlash, however much people like its products. Why else is Bill Gates backing a robot tax and Mark Zuckerberg a state-funded basic income for people who may lose out from automation? They are seeking to defuse that anger in advance, to preserve capitalism by offering reforms to it.

May seemed to be attempting something similar when she first became leader, talking about standing up for those battered by the winds of change. But her Conservative party now looks woefully behind the curve of this argument, even though it, of all parties, should understand the instinct to conserve.

The answer to renewing capitalism, by ensuring that the benefits of growth keep being shared as widely as possible even when working life is going through seismic changes, doesn’t necessarily have to be a robot tax. The idea still has holes in it that you could drive a truck through.

How do you identify precisely which companies should pay? Would it only cover technologies invented in the future, and, if not, where’s the historical cut-off point? What if many of these companies are, like Google or Amazon, headquartered overseas? What if we’re wrong and this technological revolution ends up creating rather than destroying jobs? And what are the consequences if we do this and other countries don’t, given Brexit already makes us look like a reactionary backwater? (Why, it’s almost like we need to belong to some kind of pan-European union, through which countries could hammer out agreements on stuff like this.)

But Conservatives shouldn’t mock the robot tax unless and until they’ve got something better to offer. Labour is on to something, even if it’s not yet quite sure what, and the Tories are running out of time to catch up.

• Gaby Hinsliff is a Guardian columnist and former political editor of the Observer