As far as I could understand, North American carriers charged through the nose for mobile data for the longest time, but usually bundled SMS with some plans in some form, be it a set number of messages, or unlimited nights/weekends (oof, I don’t feel younger typing that one out). I was a student working for one of our Canadian carriers the first time I saw more than like a gig of data for less than 70$/month, and that was in the long term contracts, cancellation fees days lol
In most of the rest of the world, data became cheaper faster, but SMS was/is still expensive. This, combined with iPhone’s popularity in NA making people use iMessage, led to a lot of people just sticking to the defaults and use SMS on one side of the Atlantic, while the rest used WhatsApp or similar.