What app you americans use for personal conversations?
Here in South Europe people mostly use Viber.
Edit: I was very unaware about situation in Southern Europe as I've learned from this post...
Most people in Croatia use Viber!
Really? People pay for short, unencrypted messages that can barely handle accented characters, let alone media, when there are free alternatives that are much better in the vast majority of scenarios?
Or is free sms a common thing in people's phone plans?
The problem in the US is that the iPhone has a huge amount of the market and iMessage mostly does that already. For Android to counter that you have to use a 3rd party app, which further fractures an already smaller market. Or everyone could just use sms which is free with basically every plan nowadays, which gets you by.
Like others have commented, unlimited texting has been available in most phone plans for the better part of a decade now; I'd struggle to name a place that offers plans without it.
As for the accented characters, that's something I personally don't encounter much as a native English speaker. I obviously can't speak for those who do need those keyboards, but for me it's not a problem.
With regards to encryption/privacy, I can't say that's a concern I've personally had regarding my texts. Could the government read my messages? Probably, but all they're getting is cute cat pics and random chatter about games and food and whatnot. Again, that's another aspect that's probably more of a concern for people in more sensitive situations, but I can't speak for them.
USmobile still offers non-unlimited plans. I thought ting did as well, but I guess that changed at some point. But I think I've only heard of one person using USMobile.