“The resolution also calls on the commission to encrypt travel information on the Clipper card, which can be read by scanning it with a smartphone app called FareBot. Randy Rentschler, a spokesman for the transportation commission, said he did not see the need for the legislation. Use of the card, accepted by every major Bay Area public transit system, is soaring with 689,000 transactions a day and more than 1 million active Clipper cards. Every time a user swipes the card for BART or Muni, the information is saved. In 2010, California enacted a law limiting the use of data collected on bridges and toll roads through FasTrak devices, but Clipper cards were not included in the legislation.”
https://www.baycitizen.org/news/transportation/supervisor-seeks-more-privacy-clipper/