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Phone numbers can be trivially changed.

In the article this is in the context of fraudsters buying used phones to fake rides in China and take advantage of incentive programs to make money. So they want to track these devices as they change hands.



Phones can change ownership too, so even if you can identify the phone it is dangerous to assume that you have identified a person.


If you can buy a new phone for $5 and the referral bonus is $20, there's $15 arbitrage to be made just by buying up as many phones as you can.

So I think their goal is not so much about identifying people, but identifying devices in order to prevent this loophole.


But can you buy (even a stolen) iPhone for USD 5?


The question is, can you buy it and sell it again with less than a 20$ loss


Yup, no question. I'm not claiming Uber's approach is flawless, I'm just describing what I believe they were doing and why.




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