The Labour leadership contest has been largely bereft of debate about the party’s future policy platform. Recognising the shift to the left during Jeremy Corbyn’s leadership, the main contenders have mostly promised to adopt the major planks of his programme, especially in economic policy. In the wake of a severe defeat, it is comforting for many to imagine that a less error-prone leader and the end of the Brexit dilemma will, by themselves, restore Labour’s fortunes.

Keir Starmer and Rebecca Long-Bailey have pledged to retain Corbyn’s programme of nationalisation, while Lisa Nandy has been both in favour and against it at various times during the race. But just as in 2010-15, when Labour embraced austerity – leaving it unable to argue for either Keynesian economics or social justice – the party risks once again learning the wrong lessons from its most recent defeat.

Public ownership ought not to be controversial: water, rail, mail and energy networks are state-run in many European countries and across the world. Britain has been an outlier in the degree to which these industries have been privatised. Between 1980 and 1996, the UK economy accounted for 40% of the receipts from privatisation across the OECD (which includes the US, Canada, Japan, Australia and New Zealand as well as most European countries).

Labour failed to put forward the argument against the privatised utilities. As research from the University of Greenwich has shown, the water companies alone have returned nearly £50bn to shareholders since privatisation began. Between 1990 and 2017, United Utilities delivered returns of over 5,000% percent to its shareholders - while FTSE100 shares returned an average 900% percent over the same period. This was for taking few risks and bringing little innovation, simply plundering the public.

Utilities should be low risk and low return; these returns simply demonstrate the grand scale of wealth extraction from ordinary citizens by greedy monopolists, morally indistinguishable from theft. It is a national scandal, and Labour should promise a full, judge-led public inquiry.

It is plain that privatisation has been a bonanza for shareholders and a disaster for ordinary people, not least because the receipts were frittered away on tax cuts rather than invested in infrastructure and public services. But since it has already occurred, would it be the right response to take these industries back into public ownership? The short answer is no.

The costs of nationalising the water companies, energy networks, Royal Mail and the railways runs into the tens of billions (though far less than the widely discredited pre-election claims of the CBI and the Conservative Research Department). At the same time, after a decade of austerity, the demands for public capital from core public services are immense. The backlog maintenance for the NHS alone runs to £6.5bn. So the question is not one of principle but of priorities. Labour’s fiscal credibility was seriously dented by promising that everything was possible, with seemingly limitless increases in public expenditure.

Rather than abandon its ideals, Labour needs to be more imaginative in explaining how these promises can be fulfilled. The water companies, energy networks, and Royal Mail should be reincorporated as public benefit corporations, required to place the public good ahead of profits. The state could hold a “golden share” that would enable it to appoint the non-executive directors who would be tasked with securing the public interest. The corporations would be privately owned but their purpose would be the public good.

Such an approach would promote economic justice better than nationalisation. Shareholders’ equity would be stranded in companies that would no longer pay out excessive dividends funded by debt rather than profit. The value of their shares would inevitably drop as public benefit, rather than profit maximisation, became the primary purpose. It would be a fitting price to pay for so many years of exploitation. And it would cost the public purse next to nothing.

At the same time, Labour should turn its attention to the new frontiers of common ownership. Platforms such as Uber and Deliveroo have reinvented 19th-century forms of exploitation in the 21st century. They have monopoly-like characteristics because of what economists call “network effects”. They are more valuable as they grow because they become more useful to the consumer: a taxi app that has more drivers, for example, allows consumers to find a ride more quickly.

The monopoly characteristics of these platforms means companies are able to exploit their power. Uber, for example, takes a large percentage of the ride simply for matching people who want transport with those providing it, even though the drivers bring the majority of capital employed by the company since they themselves own their vehicles. Indeed, there have been ongoing battles over whether Uber drivers or Deliveroo riders are employees or not.

Crucially, however, the platform model is primarily a business innovation, as opposed to a technological one. These companies use existing common-purpose technologies – such as GPS and smart phones – but do not have any proprietary technology. This matters because it means that if the government changes the terms of their licences to operate – for example, requiring that they become mutuals or cooperatives, that 50% of their profits must be shared, or that their fees are capped – then if the existing companies won’t agree, new firms can enter that will accept a fairer deal for workers. Such an approach would update common ownership for the 2020s, rather than simply winding the clock back to the pre-Thatcher era.

Many activists on Labour’s left are fearful that a new leader will mean the party shifts to the right in the name of electability. But the correct response is to move forward, not insist that the party stays where it is by doggedly sticking to a programme that was rejected by the electorate. Now more than ever, the left needs fresh and creative thinking that holds fast to its ideals, while finding new ways to secure them. Anything less would be the real betrayal of the renaissance in left thinking over recent years.

• Tom Kibasi is a writer and researcher on politics and economics