https://arstechnica.com/apple/2023/12/imessage-will-reportedly-dodge-eu-regulations-wont-have-to-open-up/
iMessage isn't popular enough with businesses to force interoperability.
If they would have spent the same amount of money
They did spend the same because they were getting the deal phones from their provider. You’ll have to bear in mind this switch was about 10 years ago.
I think what you’re saying contributes to why this Android/Apple discussion is still going on.
The level of Android device varies based on cost affecting the experience. If you buy an Apple you don’t have that issue because all their devices run relatively the same and are expensive. They don’t have a “cheap” option.