This is uniquely an issue in the U.S. because there are plenty of popular cross-platform competitors that are widely used in Europe: WhatsApp, Signal, Telegram.
iMessage is unpopular in Europe precisely because it's not interoperable and your friend group will look at you funny if you want to use some stupid system that only works on iPhones.
Nobody uses SMS for anything here, aside from notifications from businesses and such.
The issue is that if Google does create a competitor, or an open standards competitor is created, like RCS vs iMessage, Apple isn't going to implement that, or in any way interoperate with it. So even if Google or someone else made a better system that worked beautifully on Android and any hypothetical alternatives, but Apple only implemented their own system and refused to share, things would remain shit. Which is exactly where we are.
Apple doesn't want to live in a world where multiple brands and types of mobile phones operating systems exist harmoniously. They want to intentionally make life difficult for anyone who didn't buy an iPhone. In the process they make it intentionally difficult for people who did buy an iPhone, because their communications with non-iPhone friends are hampered.
They're also egging easily influenced teenagers on to shame other teenagers for having "worse" phones and creating unnecessary divides and unhappiness among friends. All so kids will bully other kids into buying iPhones.
None of these features are difficult to invent or implement. They should all be open standards and iPhone users and Android users should all together be angry at Apple for putting a malicious profit motive above the creation of a smooth and universally interoperable user experience.