In the US, people overwhelmingly use SMS/MMS/iMessage by default. It works with every phone, it's the one platform that people won't say "I don't have that" to.

Yep, and I like it this way.

I've no doubt it may be the case in the US, I did not mean to suggest it's not. It simply doesnt have the same sway everywhere.

I don't know literally a single person who uses SMS/MMS/iMessage where I live. And it's been this way for years. It's easily 99% whatsapp/messenger/discord etc. It's pretty openly joked about that the only thing SMS is still for these days is spam/marketing/political messaging.