6 points
itβs using SMS so it can cost people money to send messages
This is basically the historical and cultural reason why the US uses SMS and MMS: basically every phone plan has unlimited SMS before smartphones became popular, so any smartphone OS needed to seamlessly support it for adoption. Apple successfully bridged that SMS interface into a proprietary messaging protocol and app even while maintaining backwards compatibility with SMS and MMS, but not the new standard that came out after the iPhone.