Many thoughts have been spent on creating the decentralised, minimum-knowledge contact tracing approach DP-3T. This has been implemented in contact tracing apps of several countries, e. g. the German Corona-Warn-App. Following this approach, there is no central instance that can identify users’ contact history.
However, as the apps depend on specialised APIs provided by the Google Play Services (Android) and amended iOS features, my question is:
Can Apple and Google, e. g. by logging the API usage, bypass the decentralised approach? In effect, can they create contact history profiles?
Please note: This is a theoretical question about the implementation that I do not understand. I do not imply that there is any abuse of this kind; I just wonder if it would be possible technically.