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) the costs are often insane and can reach more than a dollar per message. Basically providers in those countries stopped competing with apps like Whatsapp. They still offer a texting service, but they're not trying to get someone to use it, because they already lost the battle.