WMATA Responds
Earlier I wrote about the DC Metro Smartrip Cards. WMATA responded that their entry/exit data is by time/date/location. They also responded that they do associate credit card data with a given Smartrip card when it is used to add value to the card.
They said they keep their data for 12 months in an active format, after which it is archived. It thus appears that they know who you are and where you have gone. Forever.