Unfortunately, iMessage's proprietary format is far more common than RCS in the US, it works better than RCS, and apple makes a lot of money using it to keep people tied to their ecosystem, so it's unlikely anything is going to change without government action
Though I wouldn't say Androids get it. More like Google Messages and a very few select apps get RCS. It's a standard protocol in theory. In practice, not so much. I think there's like 3 total apps. You'll probably never see a FOSS RCS app, or one that isn't tied to a big corp. Server implentations of RCS also aren't standard, but most use Google Jibe.