Earlier quoted context omitted.
Yea I think the US is definitely an outlier there; Out of the couple dozen countries I've visited recently outside of the US, Whatsapp seems like hands-down the most popular messaging app (whereas in the US, almost no one I know uses it unless they're in frequent contact with a non-trivial number of foreigners).
A major difference is that in the US text messages and MMS are usually free, so there's not a lot of pressure to move to a different communication medium. In lots of other countries you pay several cents for each individual text message and MMS cost several tens of cents. And this is for domestic messages. With international messages (which you often use because you're country is likely to be much smaller than the US…
I'm not sure that's true. At least in my sample, there are quite a few people who explicitly ask you to use some chat app instead of texting them, because they don't pay for unlimited texting.