- The author worked for LA Metro, analyzing movement patterns of millions using farecard and commercial location data to improve transit.
- Location data, though anonymized, can uniquely identify individuals with just four spatiotemporal points (de Montjoye's research).
- Commercial location data is a market accessible to both public agencies (transit) and law enforcement (ICE, DHS), raising privacy concerns.
- Digital trails no longer fade; they are copied, stored, and sold indefinitely, enabling persistent surveillance.
- The author reflects on personal complicity and the ease with which shared location reveals daily life, even through family sharing features.