Your (attempted) solution illustrates the potential dangers of data collection. There are many companies with some timestamped location data about you: cell ph

Your (attempted) solution illustrates the potential dangers of data collection. There are many companies with some timestamped location data about you: cell phone company, email or social media, credit card company, etc. Just a bit of that data combined with Smartrip data would de-identify you as the owner of that card, and all of your anonymity about your metro trips is lost. For example, three or four trips where you used a cell phone at either end of the trip; credit card purchases in different locations; maps directions on your phone; or so on. This is not far from plausible. I could see the DC Metro naively choosing to sell "de-identified" data to third parties, who can also purchase e.g. credit card data.