Sharing a sidewalk with one of DoorDash’s delivery robots is a bit like getting stuck behind someone playing Pokémon Go on his smartphone. The robot moves a little bit slower than you want to; every few meters it pauses, jerking to the left or right, perhaps turning around, then turning again before continuing on its way.

These are the sidewalks of the future, technology evangelists promise. Autonomous delivery robots, once the exclusive purview of 1980s sci-fi movies, are coming to a city near you, with promises of reduced labor costs, increased efficiency and the reduction of cars.

But as robot fleets proliferate – Starship robots perform food deliveries for DoorDash and Postmates in Redwood City, California, and Washington DC, while Marble robots will begin making deliveries for Yelp Eat24 in San Francisco on Wednesday – the question none of these companies seems to want to answer is this: are these the sidewalks that we actually want?

Sidewalk-traversing robots are one of several possible solutions to the pesky problem of “last-mile” logistics. Venture capitalists have poured millions into startups employing an army of independent contractors to provide instant gratification to urbanites. But the humans in this equation remain a significant cost, and innovators are looking to obviate them with automated solutions.

Amazon, UPS and Google are all working on an airborne method, which certainly makes for splashy PR stunts. But in cities, ground-based delivery services are a more practical solution.

Drones simply don’t make sense for urban environments, said Matt Delaney, one of Marble’s three co-founders who called robots “the only sane solution”. He argued that delivery robots could improve quality of life for people like his grandfather, who lost his driver’s license and has to hire someone for tasks like picking up prescriptions at the pharmacy.

With just a handful of robots in service in Redwood City and San Francisco, Marble and Starship have yet to face any backlash. But the revolutionary promise of robot deliveries will only be realized if these companies achieve scale – a Starship spokesman promised “thousands and thousands of robots in thousands of cities around the world” to the San Jose Mercury News.

But will those robot legions disrupt the fabric of urban neighborhoods? Are pedestrians prepared to jostle for space between robots the size of a golden retriever (Starship) or a filing cabinet on wheels (Marble)?

Delaney, noting that his robots were being programmed to behave with “courtesy” to pedestrians, pointed out that “the sidewalk is an infrastructure that is barely used”.

Renia Ehrenfeucht, a University of New Mexico professor and the co-author of Sidewalks: Conflict and Negotiation over Public Space, agreed with Delaney’s diagnosis, but raised concerns about what the best use of that infrastructure should be.

“If there really were hundreds of little robots,” Ehrenfeucht said, “they would stop functioning as sidewalks and start functioning more as bike lanes. They would stop being spaces that are available for playing games or sitting down.”

Ehrenfeucht pointed out that 130 years ago, streets were not yet divided into lanes for traffic, parked cars, pedestrians and bikes, and that the introduction of robots to the streetscape might require a reimagining of the available space, possibly with a designated lane for robots.

Sidewalks are often a hotly disputed space, and conflicts are bound to arise as new uses are proposed. Many cities across the US have adopted sit/lie ordinances, which criminalize resting or sleeping on the sidewalk and are generally considered to be targeted specifically at homeless people. At the same time, urbanists have tried to promote new uses of sidewalk space with features like “parklets”.

“We really see this as a privatization of the public right of way,” said Nicole Ferrara, executive director of pedestrian advocacy group Walk San Francisco, who wants to ban robots from the sidewalk. Ferrara argued that walking has social, health and economic benefits, while robots could pose a hazard to senior citizens and people with disabilities.

“We’re not excited about the idea of engineering walking out of our lives,” she said. “People live in urban centers not because they want to sit at home in their house and have their toothbrush delivered to their door, but because they have a pharmacy around the corner that they can walk to.”

There’s also the spectre of whether these robots will put people out of work – a sensitive question in a world gripped with anxiety about automation-fueled unemployment.

As a Starship robot jolted its way through downtown Redwood City on a recent afternoon, an older man in a blue blazer approached the robot’s entourage (a robot handler, a Starship manager, a DoorDash PR person, an external PR person, and a reporter) to enthuse about the headaches it would help businesses avoid: “No workers comp, no discrimination claims, no whining!” he exulted. “You don’t have to worry about Obamacare with this guy!”

“We don’t know him,” one of the PR staffers quickly interjected.

DoorDash argues that the robots won’t compete with their delivery drivers because the robots handle jobs that most drivers don’t want: small orders within a limited radius.

Delivery robots are also creating a new category of jobs because neither company’s model is fully autonomous – yet. Both Starship and Marble employ chaperones who walk behind the robots, answering questions from the public and intervening if disaster strikes. The robots also have remote operators who can take control if necessary.

If pedestrians do want a say in the future of sidewalks, they will have to act quickly. Starship has successfully worked with legislators in Redwood City, Washington DC, Virginia and Idaho to pass legislation that suits its requirements. (The company helpfully provided Redwood City with a copy of the language it got approved in DC, according to the city’s economic development manager, Catherine Ralston.)

But it will likely take longer for city dwellers to notice the impact of delivery robots on their day to day lives, said Ehrenfeucht, who said that regulation will likely only come after widespread adoption, as it did with other disruptive technologies such as Uber and Airbnb. That comparison carries a warning.

“Once we give up space,” Ehrenfeucht said, “it’s hard to get it back.”