A single stable identifier would've solved the whole situation and Apple already had it with Advertising ID. Exposing that to the browser would've been enough so Safari could've been ahead of the curve.
Yeah, all you need to do is include a persistent identifier shared across all sites in the world! In fact, this solution is so great you don’t even need cookies anymore and you never get logged out if you accidentally delete them!
Is this sarcasm? The Advertising ID system is from Apple and in use in all apps, and it can be reset at anytime. It increases privacy, security, and efficiency.
Yeah, it’s efficient alright. Therefore the advertising ID is only accessible to apps that have declared their interest and these have to meet specific requirements. Not just any random website.
I don’t care what you or your industry today decides it ’needs’, you’re not getting a persistent webwide tracking ID.
Advertising ID is Apple's own standard and already in use. It's what mobile apps use but it's the most privacy conscious method since it has no personal details and can be reset at anytime.
Making that available for apps and websites would've eliminated 99% of cookies and user syncing pixels since the industry could use a short-term stable ID to track engagement and conversions.
Unfortunately the industry doesn't work like that, the name of the game is "collect everything and anything at any cost".
It is so bad that there is barely any difference between the behavior of "legal/legit" players (established advertisement businesses like Google) and scammers, Google for example bypassed 3rd party cookie restrictions on Safari, just like sophisticated scammers use any means to collection information on their targets for social engineering.
What this means is that not only there is no reason to believe that advertisers will be happy with a short-term stable ID akin to Apple's Advertising ID, they have time and time proven to go above and beyond to track users by any and every mean possible.
So what introducing something like Apple's Advertising ID to web will do is merely add yet another identifier to endless bucket of targeting methods already in use, sadly, it won't make advertisers stop abusing other things like cache so we can have nice things.
That's exactly how the industry works. I've spent more than a decade in it. We're talking about IDs, not tracking other information.
IDs are needed for 2 primary reasons: controlling ad frequency and attributing clicks and conversions to an ad impression.
Cookies worked for a long time but they were always considered loose short-term and anonymous identifiers. Apple had a opportunity to offer a better device-level option that had the same privacy but much better efficiency, and yet decided to break APIs and user experience instead, while also entrenching the big companies at the detriment of everyone else.