Mike Isaac’s Super Pumped (p. 183) describes scams in China seeking to steal sign-up incentives:
[I]n China, drivers and riders colluded to scam Uber out of billions in incentives, divvying the rewards. Most scammers found each other over text-based Chinese internet forums, a simple, anonymous way to match people who wanted to make a quick buck. They developed their own codified language; drivers seeking a fake ride would ask for “an injection,” a reference to the small, red digital pin that signaled a user’s location inside the Uber app. A “nurse,” or scammer, could respond in kind to give a “shot” to the original poster by creating a new fake account and going on a fake ride with the driver. The two parties would then split the bonus incentive payment from Uber. Repeated over and over across dozens of cities, small driver bonuses mushroomed into millions in squandered cash.
The obvious solution was to better verify drivers and passengers, to prevent repeat signups. But this was off the table:
To juice growth, Kalanick had made the new user sign-up process as simple as possible. Joining Uber only required a name, email address, phone number, and credit card number, all of which were easily replicable. Fraudsters simply entered fake names and emails. Then they used apps like “Burner” or “TextNow” to create thousands of fake telephone numbers to be matched with stolen credit card numbers. But requiring Chinese users to add other, more precise, forms of identification would add more friction to the process. And, as Kalanick’s data scientists found in their research, adding friction slowed growth. For Kalanick, putting a dent in growth was not an option.
Isaac then explains the additional methods scammers implemented to create fake riders, including cheap cell phones and disposable SIM cards to simulate additional personas.