I first learned that supercookies (AKA perma-cookies, PrecisionIDs, or the more generic term tracking headers), were being used by mobile carriers to track people traversing their mobile networks in 2014. The rationale behind tracking is to provide better advertising content. Whether that’s okay depends on which side of the privacy fence you stand.
Nader Ammari, Gustaf Björksten, Peter Micek, and Deji Olukotun, staff at the digital-rights organization Access.org and authors of the paper “The Rise of Mobile Tracking Headers: How Telcos Around the World Are Threatening Your Privacy” (PDF), informed me that tracking started much earlier, in 2000 to be exact. Dr. Kevin Fu, professor and medical-device security researcher at the University of Michigan, noticed his wife’s phone was leaking information to web servers.