Apple have built up a reputation for not knowing this about me as a consumer.

Maybe they do know lots about me, maybe they don’t. A significant part of their public reputation rests on their respecting privacy concerns however. So if it turned out that they were secretly collecting data on me they would take a hit to their public reputation and (very likely) their bottom line.

They are very much incentivised to keep my data private and imho that offers a strong likelihood that they’ll actually do so.