I received a $30 credit from Uber when I installed the app. That's free money. However, Uber only lets me spend it on my first Uber ride. So I can't just put that $30 into my bank account. In my case, it was raining one day, and I didn't have an umbrella, so I called an uber and got a short ride home. It came to $8, which used up my $30 credit. I didn't cleverly hatch a scheme with the driver.
If I were in China, I could say, hey, dude, bill me $30, it's coming off my new user credit anyways. Then give me $10. The driver makes $20 instead of $8, and I make $10 instead of $0. The loser would be Uber. Now, if I were to make a criminal enterprise out of it, I could say, hey, why even get a $8 ride? Let's have NO rides, and just keep billing $30 to get that juicy new user credit! We'll get keyboard farms to keep creating new uber accounts and riding and get that sweet $30 snatch!
Now, in the U.S., Uber stops me from creating new accounts on my own to take that $30 repeatedly because it requires a credit card. Now, if I were savvy, I'd use a new credit card with a cousin's billing address on a wiped phone and create a new uber account. If I have 12 credit cards and 12 cousins, I could register 12 new accounts. The only overlap would be my name, but Uber has zero way of telling if two John Smiths with different credit card numbers and different billing addresses could possibly be the same person. They rely on the fact that no one cares so much about $30 to bother with wiping their phone, swapping in a new sim card, using a new card and a cousin's address. And, they're right, in the U.S. In China, people will go through a lot more hardship for less. Clickfarms in China pay something like 10 cents per hour.