Couriers with Postmates are the latest gig workers to rise up against the company that gives them assignments.

A few days ago, the San Francisco delivery company restructured its pay rates, which many workers said cut their incomes by about 30%. More than 1,200 couriers have signed a petition protesting the changes.

Their protest follows other backlashes this year from independent contractors dismayed about their pay and working conditions. Uber drivers in 17 cities took to the streets and turned off their apps two days before the ride-hailing giant’s Wall Street debut, generating immense publicity. Instacart shoppers — the workers who pick items at grocery stores for customers — mounted weeks of protests after the San Francisco grocery-delivery company started using their tips to subsidize what it paid them — and won a reversal.

“It’s meaningful and impressive that these gig workers are trying to imagine better futures for themselves,” said Katie Wells, a postdoctoral fellow with Georgetown’s Kalmanovitz Initiative for Labor and the Working Poor.

She sees the gig protests against the background of other recent labor movements such as the Fight for 15 campaign to raise the minimum wage and numerous teachers’ strikes and actions in the past two years. “These little seeds being planted of this global digital picket line didn’t come out of some random garden,” she said. “The fact that workers are rising up makes sense; it’s not an anomaly.”

Veena Dubal, an associate law professor at UC Hastings who studies gig workers, said the grassroots actions stem from workers’ frustration with the glacial pace of change, and the fact that mandatory arbitration agreements bar them from going to court in class actions.

“They’re just so tired of waiting for the law to fix things,” she said.

Founded in 2011, Postmates delivers restaurant meals, groceries, packaged goods and other items via independent contractors who operate their own cars, mopeds, bikes — or even skateboards. The company said in a February filing that it has 240,000 couriers.

Postmates’ pay changes, which varied by city, involved reducing or eliminating the base rate per job, lowering the per-mile rate and increasing the per-minute wait time rate by one penny, to 7 cents a minute, according to Working Washington, a labor-backed group. Working Washington helped organize the protest, as it did for Instacart shoppers. The petition asks for a transparent pay structure and pay of at least $15 an hour plus expenses.

“I used to get a minimum of $5 a job, but this weekend I got $3 and a few cents for making each delivery,” said Muhammad Mahmood, 28, who drives evenings and weekends in San Jose to supplement his income as a hardware test engineer. “I am thinking of switching to another service like DoorDash.”

DoorDash, like Instacart, has drawn controversy for offsetting driver pay with tips.

Postmates said that four-fifths of its couriers work fewer than five hours a week and that it’s collaborating with policymakers and labor organizations on new worker benefits. It also said it would welcome direct communication with Working Washington.

“What recent innovations, reduced pickup times, and route efficiencies reflect is an increasing rate of deliveries a Postmate can choose to make in a given hour, increasing cumulative payout averages from $18/hour in 2018 to $19/hour in 2019,” Postmates said in a statement.

Mahmood said his earnings even before the pay changes were much lower than that, averaging around $10 an hour. So did David Babtkis, who drives for Postmates in Los Angeles and said he made about $10 an hour before the changes.

Babtkis said his pay plunged by 25% this weekend but he hadn’t received any advance notification.

“I feel powerless,” he said. “It only hurts the poor. There are no rich people working for Postmates.”

Postmates, which has raised $678 million in venture backing and is worth $1.85 billion on the private market, disclosed in February that it had filed confidential paperwork for an initial public offering this year. It has not yet said when that might happen, but it’s logical that Postmates could be prepping for its offering by reining in costs.

Wall Street’s appetite for companies that lose money appears to be waning, as both Uber and Lyft, the gig giants that went public in recent months, have seen their stock prices nose-dive.

Michael Reich, an economics professor and co-chair of the Center on Wage and Employment Dynamics at UC Berkeley, said companies like Uber and Lyft can easily afford to pay drivers more and treat them as employees with benefits. That is something those companies are fighting in several arenas, most notably California, which is weighing legislation, AB5, that would turn many independent contractors into employees, codifying a recent California Supreme Court decision.

Reich co-wrote a study for New York City last year about driver conditions there, based on data the city compelled Uber and other companies to provide. Their pay is so low that 40% of drivers qualify for Medicaid and 18% qualify for food stamps, the study found. That led to New York enacting the nation’s first minimum wage laws for drivers, the most-dramatic change so far in any gig workers’ conditions.

From its enactment on Feb. 1 until April 28, that policy increased driver pay by $152 million, according to the city’s analysis.

“Word has gotten out in other cities, undoubtedly leading to further protests, which I expect will continue,” Reich said.

Carolyn Said is a San Francisco Chronicle staff writer. Email: csaid@sfchronicle.com Twitter: @csaid