Even if this is true, there's a significant difference in that Google would lose nearly every single one of GCP's customers if it was ever proven they were mining data of their customers' cloud services.

And at the very least, it is much harder for Google to correlate a competitors' account systems and user data with their own profiles they use for ad targeting.

And of course, most importantly: Apple collects a lot less data when you use their apps. For instance, Maps data is never associated with an Apple ID, and significant work is done to fuzz and scramble the anonymous data they store to avoid it being possible to turn it into data about a real person. In comparison, Google Maps logs your location to your Google account every five minutes.