To give a counter example, here in Sweden, SMS&MMS are used quite a lot. Including bidding for housing. And it's not due to a lack of alternatives.
For anything else, using SMS is like using Notepad to write books. Many better alternatives have come through in the decades since that tech was new.
It feels very weird to have both a very good end-to-end encryption (the Signal encrypted messages) and a very bad system (SMS) together in the same app. People should just move away from SMS, it's not like it's hard.