As a European living in the US, it's been baffling to me. Everywhere else in the world people use WhatsApp, Telegram, Signal, etc. This iMessage green/blue bubble nonsense just isn't a thing outside the US.
My understanding is that unlimited SMS text messages have basically been included free with cellphone plans in the US for a very long time while that's generally still not the case in Europe. So there hasn't been a need to find a cheaper way to send messages.
Apple has 56% of the US market compared to just 36% in the EU, afaik the number gets even higher as you go younger so the clique-iness is a lot stronger.
I mean, isn't this just trading one bad monopoly for another? It's weird to me that everyone's like "oh, the backwards US where they gave in to the Apple monopoly. We enlightened rest of the world use Facebook's Whatsapp like real free people".