Why Consent Fails in Practice: Lessons from Web Measurement Studies
summary
A custom crawler instruments 7,000 California publishers to click banners, send a Global Privacy Control header, log IAB/GPP/USP APIs and HTTP requests, and monitor ~2,000 third‑party ad scripts; results show 85% of ad scripts ignore consent APIs and only 9% call them consistently, while about 15% of publishers misencode GPC so opt‑outs appear as opt‑ins and several dozen sites conflict on selling vs sharing bits, leaving opt‑out signals poorly propagated to top advertisers.
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chapters (10)
- 0:00Consent challenges on the web
- 1:36Consent choices ignored
- 4:05Measuring consent failures
- 5:52IAB consent APIs adoption
- 8:20Third-party scripts ignoring consent
- 9:02Global Privacy Control issues
- 10:26Conflicting consent signals
- 12:11Opt-out signal propagation
- 12:56Simplifying consent ecosystem
- 15:44Conclusion
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