International messaging is still relevant in many parts of the world that don't necessarily need to message neighboring countries, but have a big diaspora.
Yeah, but the US is pretty insular. Times are different now, but my grandparents who immigrated basically didn't communicate with the old country in my lifetime.
If roughly 15% of the US population is immigrants [1], and not all of them communicate across borders, and very few non-immigtants communicate cross borders there's not a whole lot of demand for a product that reduces costs of cross border messaging in the US.
As an early employee if anyone knew about WhatsApp, they almost certainly were a younger immigrant. Everyone else was like 'why would I use that?, I have unlimited texts' or they were using BBM.
Sure. Americans with close or many international contacts almost certainly use an internet-based chat/voice app with those contacts. That's not a large enough percentage than any one messaging app is a viable option for a group chat involving a dozen randomly-selected Americans. Almost every time, one or two of them will steadfastly refuse to install any app and insist on using MMS.
