Drivers who find gigs through virtual labor marketplaces, however, often have control over little else. Uber and Lyft, for instance, each set the rules and rates for drivers who use their apps and typically take a 20 percent commission on fares. The apps also offer complex incentives to drivers — with reduced fare pricing during certain promotions, increased fares for certain neighborhoods during peak commuting hours and bonuses for people willing to drive for 30 hours a week or more.

A spokeswoman from Lyft says the company has given its drivers tools to put them “in control of creating a schedule that works best for them.” Those tools include weekly earnings forecasts and real-time earnings updates. At Uber, drivers can sort their earnings over different time frames — a day, week, month or year — and examine their entire trip history, a spokeswoman for that service says.

Even so, some drivers say that, when they do the math, they have found that they earned less than they had expected.

Image Jianming Zhou, the other co-founder of SherpaShare, met Mr. Pierce in early 2014. Today, their company has more than 10,000 active users including drivers who work for Uber, Lyft and Sidecar, and for food delivery services including Postmates, Fluc and DoorDash. Credit... Alexis Cuarezma for The New York Times

Niki Payne is a writer and social media consultant in Los Angeles. A few of her clients occasionally pay late, she says, and she wanted to build up a financial buffer, so she recently started driving with Lyft. When she heard a few weeks ago that Uber was offering a $500 bonus to attract drivers from competing services, she signed up to drive with Uber, too.

During the week of April 13, she made 22 trips for Lyft over the course of 35 hours and ended up making $311.40 in tips and fares after Lyft took its commission, she says. During the week of April 20, she tried to earn more by making herself available to drive for about 41 hours so she could qualify for Lyft’s 10 percent bonus. Although she made a little more, $321.66 after the Lyft fee, her pay actually declined to about $7.85 an hour from about $8.90. And that was before she factored in taxes or her weekly extra gas cost of about $50. The minimum wage in California is $9 per hour; but it applies to company employees, not independent contractors.

In the past, Uber and Lyft experimented with hourly earnings guarantees for drivers who met certain conditions, such as accepting 90 percent of ride requests and completing at least one trip an hour, in Uber’s case. Some drivers, however, say they did not like that incentive because it made it nearly impossible for them to work for multiple services at once.