the poor countries use WhatsApp mostly due the fact that sms was costly.

so you're tryna to monetize against businesses serving poorer users. yes - they maybe more in number but margins are razor thin.

the richer countries where margins are higher - sms, email, etc are cheaper & permission less. so eventually most providers most settling on email & sms/rcs.

Maybe I need to start looking at SMS/MMS proper, but that's putting a lot of information in the clear and giving up a lot of features.