TL;DR
- Users who have rooted their phone, have their bootloader unlocked or are using some custom ROMs report that their RCS messages are not being sent, even though RCS shows them as connected.
- The Google Messages app does not show any error messages when blocking RCS messages of these users and does not send the messages out as SMS or MMS either.
- Google famously campaigned for Apple to include RCS messaging in iMessage but is now blocking it for certain Android users.
Anecdotally it’s obvious everywhere you go. I travel all over the world often and it’s always WhatsApp. The taxi drivers, the hotel people, everyone.
For actual studies I found a handful with a quick google that confirm it. Whatsapp reported 2 billion users in 2020. And then WeChat is the next which is China centric. Nobody uses standard SMS except Americans.
https://engage.sinch.com/blog/most-popular-messaging-apps-in-the-world/