Global Web, Local Privacy? An International Review of Web Tracking

A new study by Harry Yu, Patton Yin, and Sebastian Zimmeck, published on arXiv (2604.18633), evaluates web tracking across ten countries using the Common Top 525 and Country-specific Top 525 sites. The researchers found that opt-out jurisdictions like Australia and California have the highest levels of tracking, while opt-in jurisdictions under GDPR show significantly lower levels. Specifically, EU countries average 50.5% fewer tracker connections on the Common Top 525 compared to non-EU countries.

Further analysis reveals that simply not interacting with cookie banners reduces trackers by 48.5% for a sample of 36 German sites. While 28% of top sites show cookie banners globally, indicating a moderate 'Brussels effect,' the study argues EU law primarily acts as a 'Brussels shield' against US ad tech practices. The authors emphasize that strong enforcement of privacy laws is key to improving user privacy online.