> do not tie them to an individual Just knowing the transit pattern for any particular ID would be a huge indicator of who the individual is. Imagine the cons

> do not tie them to an individual Just knowing the transit pattern for any particular ID would be a huge indicator of who the individual is. Imagine the consequences if you looked at my Clipper (SF Bay Area) card. I almost always get on or off at one of two specific transit stops but not any others (which would pinpoint me down to a pretty specific 1-2 block radius if you assume I use the closest stops to my home), if I take the train from downtown SF it's either to the airport or to an East Bay stop, if it's an East Bay stop I take a specific bus that goes to only so many stops...and I chose that particular bus route over others from that train station. You would be able to guess where I live and where I'm going all the time at the bare minimum. While I'm fine with this data aggregation right now since it's used for payment and proof of payment, in conjunction with your idea of selling ads and maybe a corrupt politician who wants to monetize that data for a free system... I shudder to think about super targeted ads as a result.