[dmattia]

In California under CCPA, it actually goes beyond just frontend regulation and cookie banners, and into the realm of backend tracking management: https://oag.ca.gov/news/press-releases/attorney-general-bont...

The California Attorney General ruled that if a user presents a GPC signal, the company should update all of their backend systems to opt out of tracking in the same way as if the user clicked a "Do Not Sell My Personal Information" button.

[kuschku]

And similarly, German courts recently ruled the DNT header to be legally considered rejection of tracking (Az.: 16 O 420/19)

Legal backing obviously isn't reason enough for Mozilla to support a feature.

And GPC isn't even compatible with GDPR.