If Apple really cared about privacy it would had given us iMessage for Android.
Then we wouldn't need to install Whatsapp or other junk to talk to others with Android phones.
Everyone would just use iMessage on iPhone and Android and would instantly kill all other messaging services.
Plus Android does support SMS+Messaging app integration (look at Signal) so the experience would had been similar.
They could offer an ad-based version (ads only by Apple) or a bit cut down version as an alternative.
Why would Apple care about privacy on Android devices? That's like Target worrying about liquid spills in Wal Mart aisles.
And by the way, no one is forcing to install WhatsApp, and it is in fact possible to text message Android users from an iOS device.