Doesn't HTTP has an header [0] for this? The user can opt easily in and out. I've just read the specs and find that it's being deprecated. Why? It may not be granular, but I believe anyone opting out of telemetry also does not want marketing tracking.
Yea websites straight up ignore it. Can’t currently find it but there was some wired/verge article detailing what they track of u and they actually mentioned as such too
> The Platform for Privacy Preferences Project (P3P) enables Websites to express their privacy practices in a standard format that can be retrieved automatically and interpreted easily by user agents. P3P user agents will allow users to be informed of site practices (in both machine- and human-readable formats) and to automate decision-making based on these practices when appropriate. Thus users need not read the privacy policies at every site they visit.
> Why is P3P useful?
> P3P uses machine readable descriptions to describe the collection and use of data. Sites implementing such policies make their practises explicit and thus open them to public scrutiny. Browsers can help the user to understand those privacy practises with smart interfaces. Most importantly, Browsers can this way develop a predictable behavior when blocking content like cookies thus giving a real incentive to eCommerce sites to behave in a privacy friendly way. This avoids the current scattering of cookie-blocking behaviors based on individual heuristics imagined by the implementer of the blocking tool which will make the creation of stateful services on the web a pain because the state-retrievel will be unpredictable.
> In some situations, the cookies we use to secure and authenticate your Google Account and store your preferences may be served from a different domain than the website you're visiting. This may happen, for example, if you visit websites with Google +1 buttons.
> Some browsers require third party cookies to use the P3P protocol to state their privacy practices. However, the P3P protocol was not designed with situations like these in mind. As a result, we've inserted a link into our cookies that directs users to a page where they can learn more about the privacy practices associated with these cookies.
[0]: https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/DN...