S
So there are a few things to note.
RCS is Google’s answer to the fact that's impossible to change the current establishment regarding messaging apps and what people use no matter how good your app is, no matter how big and how much money you have. Google learned this the hard way so they turned to what's essentially the next step after SMS, Google didn't invest RCS and RCS isn't even a new idea but they felt this is something they can be successful for them and they were right, now with Apple's adoption to RCS its clear that Google’s bet on RCS worked.
Another thing, RCS works automatically on Android smartphones, it doesn't need support for carriers (although recently carries actually started supporting Google’s RCS rather than their own version). Maybe at the beginning 5-7 years ago when Google started pushing RCS there were some problems, it didin't work on some phones, you needed to activate it or install Google messages , but in the last few years these issues were solved.
Regarding WhatsApp, it's the most popular messaging app in UK by far, way more popular than in the US although WhatsApp is growing in the US.
There's no reason to use Textra in 2024, you can very easily schedule messages with Google Messages, which is the default messaging app anyway and you also get E2E encryption if you have RCS turned On and use it to comunicate with other Android users. Textra is just another third party holder of sensitive data when there are already more than too many.
RCS is google trying to modernise SMS, whihc is fine if you want it, but I don't like the way it is being pushed, but that seems to be the norm these days, opt out instead of opting in and that is if you know about the opting out. I am still surprised that Apple agreed to use RCS.
The problem with services like RCS, iMessage and other message services like WhatsApp is if you lose data connection then you are stuffed unless it falls back to SMS. That is the other thing it uses data, where SMS don't. I only have a limited amount of mobile data, 4GB, but I have unlimited SMS.
Google in the early days wanted RCS to be supported by networks, so Google did not have to do anything, but networks did not bother, so Google had to intervene and that is why RCs for some networks go though Google servers. Now more networks seems to be supporting it.
Link below from Wikipedia
Rich_Communication_Services
Google messages would not schedule messages and it don't or did not have the delay I like when pressing send, I had that feature in the SMS app that was on my old Huawei and I found it useful. Unless they have put it on Google messages recently, it certainly was not on it when I last used it. Textra is just a SMS app, it don't store anything, it sends it from your phone to the SMS server. I don't send anything that important to require E2E encryption, and our government is trying to ban it anyway on all apps.
RCS turned on mean that people can send a lot of bloat, that is why I keep with SMS, it does what it says on the tin.