There are the data privacy laws that mandate users be able to opt of tracking, and it should be pretty clear to a non-psychopathic company that a person using the private mode on their browser is opting out of any tracking.
Google is one of the biggest companies in the world. Do they really need to be wringing their users as hard as they can to milk out every last drop of ad revenue potential?
That's not what incognito mode is. It literally says on the first page when you open incognito window. People want to skip reading technical details when provided but then get angry when a company does the exact thing they warned about.
Also where does this end? Should car dealerships be allowed to analyze your data? Cars you've bought, cars you test drove etc.?
A disclaimer that a technical vulnerability exists isn't some kind of implicit invitation for a company like Google to use that vulnerability for their benefit. It's true that it's technically possible to track users using a private browsing mode, but it is not ethical.
If you have a car with a broken lock, that's not some kind of open invitation to burglars to steal whatever they want from your car.
You are asking that browsers announce to websites that the user has incognito mode enabled, which immediately opens the door to websites refusing to serve users running incognito mode at all.
I think that's entirely fair: Websites should not track users who do not want to be tracked, but websites should decide whether or not to serve clients which aren't to be tracked.
Well, ideally yes, but let's be honest here. If we can't trust websites to not abuse data, how can we possibly trust them to respect a polite request not to gather the data in the first place? I would personally rather have an incognito mode feature that I have confidence performs the task it claims to do without alerting the website, than one that loudly announces its presence, on the hope that it might be respected.
I don't trust Google, but I certainly don't want Google to trust random websites on my behalf.
Google is one of the biggest companies in the world. Do they really need to be wringing their users as hard as they can to milk out every last drop of ad revenue potential?