SgtSurehand Traffic data has existed since long before cell phones, so surely it would be possible for a privacy-respecting app to make use of publicly available traffic data?
E.g., Garmin-brand GPS units (at least used to) have an option to add a traffic receiver in some regions, and those units couldn't even transmit data. It'd be quite a challenge for them to track users / not respect privacy, when there was no way to transmit data out, but they provided traffic data.