Maybe it should apply. SMS works on any carrier. Why not have an open framework that allows messaging between platforms? The reason: Because walled gardens are more profitable.
The Digital Markets Act (DMA) is coming to Europe and with it enforced interoperability of messaging software. Hopefully for 2023/2024. I'm curious to see whether companies will have the gall to implement different behaviours for European consumers and the rest of the world.
Companies implement different behaviors in different markets within the same state within the US; I think you may be giving major corporations too much credit if you suspect that deep down inside they're driven by trivial concerns like shame or genuine concern for customer opinion.