Contacs ("People") and Calendar are part of AOSP, althrough most vendors do not ship them. It does not matter, as neither AOSP nor vendor-specific Contacts or

Contacs ("People") and Calendar are part of AOSP, althrough most vendors do not ship them. It does not matter, as neither AOSP nor vendor-specific Contacts or Calendar applications contain any protocol code. These frontends use contact and calendar specific content providers, which in turn provide plugin based API for sync adapters. Google's own sync adapter is such plugin, as well as Facebook's or even Microsoft's (for Skype contacts). It is true, that there are no CalDAV/CardDAV sync adapters on the devices. However, because not everyone is interested in one, it is perfectly fine to install them from Play Store for those interested.