I’m pretty confident the blue and green colors have nothing to do with it. It’s simply the difficulties of using sms (or at least how Apple implements sms). iMessage allows much higher quality videos/images to be sent and enables group chats to be dynamic where people can be added and removed at will. On iOS sms group chats have to be made with every member in it at creation, if you want to add another person or remove a person then you have to make a whole new group chat. Compound this with iPhone dominance in North America it often presents an annoyance where the single android user forces all the iPhone users to use sms and all the difficulties/reduced features it comes with.

WhatsApp, Telegram, and whatever chat app isn’t used in NA because it’s just harder to convince someone to download and make an account. Why should a user download another chat app? Why isn’t iMessage (sms) app good enough? Usually I’ve seen people just use instagram to chat with android users because sms is just so bad (at least on iOS, I’ve heard some things about how android works around the limitations).

Yes Apple could implement better sms features but they won’t.

So don’t just parrot “it’s because of the colors” it’s most likely due to users association with past experiences of “green chat bubbles”.

Apple is still to blame here but it’s not because users are scared. Most iPhone users or phone users in general just want it to work and never think about what features they’re missing. Asking/convincing someone to download yet another app and set up yet another account to yet again be spammed by emails, texts, phone calls is just too much for a majority of people who are used to the simplicity of iMessage. It comes with your phone, you make a single Apple account, and it just works™.