>Do Americans not all use iMessage, since pretty much everybody has an iPhone there?

I'm Irish and travel back and forth a lot. First, not everyone has iPhones, Android has 40% of the market.

Older generations use Facebook to manage their clubs. I'm increasingly seeing Whatsapp and occasionally Signal for younger and more tech-savvy social circles. Facebook is non-existent in sub 35 year olds. Its just taking longer to switch over (or away from) Facebook given how tech savvy older folks are here compared to Ireland.