Earlier quoted context omitted.
Why do you believe that Google aren't tracking people? If they have the technological capability to do so they almost certainly do, even if they happen to serve non-personalised ads while doing it.
Because technology alone can’t protect your privacy. You need to trust people. Google says they don’t track ads when configured to not-track. They provide technical details on what this means. It’s designed around the General Data Protection Regulation (GDPR). At some point there has to be trust. I trust that Google won’t risk millions of Euros in fines over lying about not tracking people.
In our current world the advertising industry has demonstrated their inability to self-regulate, and even Google isn’t any better (see the recent issues regarding Android tracking locations even when the option was set to off).
GDPR is irrelevant in that case. If the tracking happens in such a way that it’s impossible to tell from outside Google then nobody will have grounds to sue.