One really weird way that you can see that is looking at Denmark, which has historically been used as a test market for telcos. SMS was practically free when iMessage was announced, not entirely, but enough people had unlimited SMS plans at that time. Denmark was the testing ground for different phones and pricing plans, better to screw up in a market with 5 million people, compared to one with 80 million.

I believe that the "free" SMSs at the time is a pretty big reason why iMessage is huge in Denmark, but not in the countries surrounding us. It's not the biggest messaging platform, that would be Facebook and Facebook messenger, not WhatsApp, Telegram or Signal. It seems like people want Europe to be all in on "alternative" platforms, but it's frequently all Facebook properties.