A Black Mirror existence: that’s how trade unionist Mags Dewhurst describes working as a rider for Deliveroo, the pre-eminent online food-delivery company. Here is a story of workers branded as entrepreneurs, which has the effect of stripping away their rights; of a race to the bottom in terms and conditions; of being managed by algorithms and apps. I sit with five Deliveroo couriers in the headquarters of the Independent Workers Union of Great Britain (IWGB), a union that has successfully fought for particularly low-paid migrant workers. They are currently classed as self-employed independent contractors, or cycling micro-businesses, and therefore lack rights all workers should be able to take for granted: the minimum wage, paid holidays, pensions, protection from discrimination, and trade union rights.

Riders speak of colleagues who have been sacked for arbitrary reasons out of their control

At the end of 2016 the union applied to win collective bargaining rights for Deliveroo riders in Camden and Kentish Town, north London, which would mean making them a category of self-employment known as “limb (b) workers”, granting them these basic rights. Three weeks before the case was heard by the central arbitration committee, Deliveroo pulled a clever stunt. The company inserted a new substitution clause in the contracts of all the workers, supposedly granting riders the “right” to allow anyone else to do their job in their place. This was farcical. A rider would have to conduct a criminal record check and an immigration check, as well as complying with other legislation – for example, to determine they had not been trafficked – on any potential substitute. This allowed Deliveroo to present riders as self-employed contractors: because after all, which worker is allowed to find a substitute to do their job for them?

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The ruse worked. Although the committee’s judgment was “99% written in our favour”, says Dewhurst, including accepting that Deliveroo drivers would neither desire nor need to use the clause, the company won on a technicality. The union is now appealing for funds to fight an appeal in the high court that will cost tens of thousands. If it loses, the union faces financial ruin – and other employers will put the same clause in their contracts to avoid paying their workers a minimum wage or giving them basic rights.

Deliveroo says it seeks to give workers fair terms and conditions. All the same, consider the accounts of its riders. Their present could be your future.

There is weak enforcement of employment law, says IWGB general secretary Jason Moyer-Lee. Photograph: Alicia Canter/The Guardian

It once was the case that they’d get training, says 24-year-old Tom, a rider from Tooting: “You’d go out on a bike with a recruitment assessor – called a trainer – who was also classified as an independent contractor.” There’s a lack of suitable training partly, the riders tell me, because that would make them look like workers, not contractors. “It’s cut-your-nose-off-to-spite-your-face lengths to twist their business model,” says Tom. “Can you imagine if they’d told investors with their original business model: ‘We’ll pick random people off the street’? Of course they didn’t!”

Most Deliveroo riders are paid per drop, pay for their own equipment and service their own bikes. If it’s a quiet time of day, that can mean clocking into work on your app, waiting around and being paid nothing. Each worker is assigned a zone – a city such as London is divided into dozens of them – to make deliveries. But the riders tell me the zones are being constantly expanded in size, meaning it takes longer to make deliveries; meaning less money.

“Everything is algorithmically managed,” says 20-year-old Guy from Brighton. “But the app is quite glitchy: you can lose your signal, your job gets unassigned, and if you get too many unassigned deliveries, you lose your job.” Such a system encourages riders to travel at dangerous speeds: once, 25-year-old Mohaan came off his motorbike and badly injured his knee cap, but continued to his destination for fear that terminating the job would get him the sack.

Those who do the most drops get first dibs to choose the most lucrative time slots to work, which is nowhere near as fair as it sounds. “You sell it to the riders in this really macho way, that if you’re really speedy and committed to the company you’ll make loads of money,” says Dewhurst. “But the reality is there are so many variables out of your control: restaurants taking too long, customers not being in, bike punctures.”

If you find yourself in a shift working for less than the minimum wage and log out, that’s a black mark, leaving you forced to get a less lucrative shift next time around.

Riders speak of colleagues who have been sacked for arbitrary reasons out of their control, including glitches in the system and mistakes made in the call centre.

As 31-year-old Barnet courier Alan puts it: “If you transfer responsibility to those without the means for responsibility, you return to Victorian piecework with no workers’ rights.”

Deliveroo presents its model as an opportunity to get an occasional bit of money on the side – pocket money even. That its riders value the flexibility. But in practice no business can work and thrive like that. The riders emphasise they’re not against flexibility, innovation or technology: they just want rights. It doesn’t take very much imagination to see how employment dystopia beckons.

As Jason Moyer-Lee, the union’s general secretary, puts it to me: unlike, say, immigration law, there is weak enforcement of employment law. You can see how the model could be expanded, to coffee chains, or clothing stores. “You could log into a Topshop app, and then join a queue to work,” Dewhurst says. It is an attractive proposition for companies, stripping out labour costs and HR. Consider that zero-hours contracts were an obscure innovation until they were rolled out across the economy. It could indeed be a Black Mirror episode. It isn’t: it is Britain in 2018. Black Mirror in real time.

• Owen Jones is a Guardian columnist