RCS is just a standard, much like how SMS is just a standard. Google’s Messaging app is just one implementation of it, though it probably is the most popular in the US it is not the only one, nor is Google able to decide who cannot use it. Carriers typically have their own, though you may have recently heard that T-Mobile decided to switch over to Google’s.

I’m American and I think food in the UK is awesome. I don’t like everything, but what I do like, I really like! Plus y’all have cute and silly names for everything, it’s great. I’m sure most Americans would feel the same way if they ever get the chance :)