Like magic mushroom spores and vials of human growth hormone, e-scooters occupy a mysterious grey area in UK law, being legal to buy but illegal to use – in public, at least. So, unless you have an exceptionally long driveway, a home filled with palatial corridors or a private airfield, the chances are that if you own an e-scooter you are a criminal. Yet sales of these illicit micromobility devices are booming. An estimated 1m private e-scooters are now in use on the country’s roads, zipping along bike lanes, weaving in and out of traffic and sometimes terrorising pedestrians on the pavement. In the eyes of their promoters, they are a one-stop solution for reducing congestion and carbon emissions, replacing short car journeys and providing crucial “last mile” connectivity to public transport hubs. In the eyes of their critics, they are “absolute death traps”, “silent killing machines”, and lithium-hungry devices whose green claims don’t stack up, representing the encroachment of Silicon Valley tech-bro urbanism on to our public realm. Paris recently banned rented e-scooters, but the effect has been to trigger a massive boom in sales of private scooters instead. While the British government dawdles over regulation, e-scooters continue to proliferate, frustrating local authorities, scooter companies and their critics as pavements become ever more cluttered and accidents soar. Currently, the only legal way to have fun on two miniature battery-powered wheels outside the house in Britain is to hire a rental e-scooter in one of the 23 trial areas in England. A two-year trial was launched in July 2020 by the Department for Transport (DfT), with the stated aim of supporting a “green recovery” from the coronavirus pandemic, seeing 12 operators unleash their fleets of jauntily coloured e-scooters in parking bays from Nottingham to Great Yarmouth. But so far the figures suggest that rather than replacing car journeys, the scooters are supplanting less carbon-intensive modes of travel. A DfT evaluation report of the trials, published in December 2022, found that the average trip length was 2.2km (1.4 miles) and took 14 minutes, placing scooting somewhere between walking and cycling. 42% of users said they would have walked if they hadn’t taken an e-scooter, while only 21% would have taken a car or taxi. The “low carbon” claims are also questionable, given the energy that goes into extracting the raw materials and manufacturing the scooters, which currently have a lifespan of up to five years – often less, given the all-weather battering they receive. A 2019 study by researchers at North Carolina State University found that riding an e-scooter typically produces more emissions per passenger than taking the bus, once the carbon footprint of production and distribution is taken into account. A 2022 study by the Swiss Federal Institute of Technology concurred, finding that, on average, a rental e-scooter creates 51g more of CO2 per km than the means of transport it is replacing. The e-scooter operators insist that such a direct carbon comparison is missing the point. “You need to look at it holistically,” says Iqbal Ahmed, UK policy manager for Dott, one of the three operators of the London trial. “E-scooters promote a multimodal, car-free lifestyle, helping people to make trips they would otherwise not have made. The tube stop might have been too far away to walk, but the scooter makes it easy to get there and take the train.” Safety remains one of the biggest concerns. Nine regions opted to cut their trials short, or not extend them, including Rochdale, Coventry and Canterbury, with reasons ranging from the menace of abandoned scooters to the frequency of accidents. Kent county council’s cabinet member for transport, David Brazier, said he decided to end the trial “before someone was seriously hurt” – after an 80-year-old woman suffered a broken wrist, cracked jaw and broken cheekbone when she was struck by an e-scooter being ridden on a pavement. E-scooters are heavy, around three times the weight of a regular e-bike, and can be difficult to control for first-time users, while their comparatively small wheels make them susceptible to the lumps, bumps and potholes that riddle Britain’s roads. The number of collisions involving e-scooters has tripled in the last two years, from 460 in 2020 to 1,402 in 2022, while there have been 34 e-scooter deaths since 2019. When measured per mile, the DfT report found the casualty rate for rental e-scooter users was three to four times that for pedal cyclists. The youngest fatality was 12-year-old Mustafa Nadeem, who collided with a pedestrian while riding on a pavement in Birmingham and fell into the path of a slow-moving bus. As the coroner noted in their prevention of future deaths report, users in the UK trials are required to have a driving licence and be aged over 18, but there is nothing to stop a rental account being transferred from one phone to another – as happened in Mustafa’s case. The parliamentary advisory council for transport safety (Pacts) has made several recommendations, should the government decide to legalise private e-scooters, including a minimum front wheel size of 12in (30.5cm), a maximum speed limit of 12.5mph, and mandatory helmet wearing. But the e-scooter industry remains sceptical. Lime says that user feedback in London, where the speed is capped at 12.5mph, is that it is too slow and makes people feel more vulnerable. Similarly, when it comes to helmets, the operators encourage and incentivise their use (Lime offers a discount if you take a selfie in a helmet), but argue that infrastructure must adapt to prioritise bikes and scooters – citing cities such as Amsterdam and Copenhagen, where cycling infrastructure is exceptional, and few people wear helmets. Still, while Rishi Sunak’s government remains intent on preserving the sacred rights of the motorist – most recently withdrawing the post-pandemic guidance for active travel – such infrastructural changes look like wishful thinking. As the government keeps kicking e-scooter legislation into the long grass, the country’s streets and pavements will continue to be flooded with unregulated machines delivered to your door with small wheels, no lights and possible speeds of up to 60mph, while the patchwork of regulated rental trials stumbles on. “The government keeps extending these trials without changing anything,” says Tim Burns, head of policy at cycling charity Sustrans. “No thought is given to the wider strategy, which makes it impossible for both the operators and the local authorities to plan. They are trying to meet pollution-reduction targets and tackle congestion, but have no idea if rental scooters will exist in five or 10 years’ time.” As long as we have a prime minister who prefers to take his helicopter over the train, the future of electric micromobility will hang in limbo, occupying a semi-legal, environmentally questionable purgatory, while both congestion and street clutter continue to rise. Oliver Wainwright is the Guardian’s architecture and design critic