Technically apple users can fix the quality issue with a change in their settings to stop compression of images sent via MMS.
As to android phones not having high quality, your def right about that. The RCS rollout was terrible. But most of the flagship devices have RCS and a lot more carriers are allowing it (here in Canada at least. I assume we’re behind the curve though)
Samsung has enabled RCS down to even their cheapest handsets, (I believe) but apple isn’t adopting that till next year, and then we’ll be able to skip the shenanigans