The US never moved past SMS for instant messaging. iMessage extends SMS seamlessly (to iOS users).
Honestly i tried using different apps with different people groups and ended up dumping all of those apps over time since they 1) sucked battery and 2) weren’t that great and 3) were either ad-supported or were free with questions on what they company was doing to stay afloat.
iMessage solves all of these issues without needing to explain anything. Occasionally i will laugh when i see granny (liked this message) knowing she uses android and had to type that out but whatever.