Amazing. If you said to someone "Hey, I wanted to know where you went after the cab picked you up last year, so I called up the cab company and asked them wher

Amazing. If you said to someone "Hey, I wanted to know where you went after the cab picked you up last year, so I called up the cab company and asked them where they dropped you off and they told me", they would be outraged at (your behavior and) the breach of privacy shown by the cab company. But the city released a dataset that allows exactly this query. What were they thinking? Something else that could be mentioned in the linked article: if someone you were with got in a cab in 2013, and they told you where they were going, and you remember the approximate time and location, you can tell whether it was their true destination regardless of how many other people were being picked up at the time, because you don't have to find the exact ride they took, you only have to see whether any rides went to the place they told you. This search is even extremely resistant to the differential privacy suggested by the post's authors. I'd be much happier simply stating that location data is not de-identifiable, and no-one should use a cab in a city that logs location data if they aren't happy with an adversary knowing where they went.