1. iOS being uncommonly popular (in other words: the US is weirdly rich compared to even most developed countries)
2. People texting a lot (maybe other countries’ carriers used to just make texting too expensive?)
Outside the US, people more commonly use messaging apps, and there is less peer pressure to be on iMessage as it is less likely for someone (in a certain social class…) to have a big majority of iOS-using peers. I had never even heard the term ‘green-texter’ until I went to the US
Yes. US mobile plans gave enormous buckets (thousands) of SMS messages a month to mobile users 10-15 years ago, so there was little incentive to move to other mobile messaging systems.
Conversely, the lack of such generous SMS allotments in most non-US countries drove widespread adoption of WhatsApp/Facebook Messenger/etc.
But I'm in the US, which has a disproportionately high amount of iOS users. Across the rest of the world iMessage would be competing with WhatsApp and its existing network (something the e-mails in the article note) and I think it would have been an uphill struggle.