[user3939382]

Google fully understands that users are reaching for incognito because they want their session to be 100% ephemeral they just don't care because they're paid to not care. Technical distinction between local and remote data is unrelated, Google could offer privacy if they wanted to.

[Almondsetat]

Google has specifically created an entire page telling users exactly what to expect from incognito browsing: it's the first page that opens when you go incognito mode, every time

[Lammy]

Relevant Scott McCloud Chrome comic: https://www.google.com/googlebooks/chrome/big_22.html (2008)

[Jensson]

Do you think browsers should send to the server that it is in incognito mode? Because that is what you are asking for, that would just reduce privacy not increase it.

[Dylan16807]

That's not the only way it could be done.

But sure, sending that extra tidbit of information specifically to servers that they can verify won't track you would be a good tradeoff.

Even worse is that they probably do try to detect if you're in an incognito session, but only for their benefit.

Edit: Here's an easy thing they could do. Even if we accept or pretend to desire cross-browser correlation at all, new-seeming browser profiles could have their information siloed for a few days and if they disappear in that time it all gets treated as an incognito session.