It is a generic accessibility problem with any UI toolkit that goes beyond the "native toolchain". However, customizing everything from drawing layer is the onl

It is a generic accessibility problem with any UI toolkit that goes beyond the "native toolchain". However, customizing everything from drawing layer is the only way to achieve any kind of UI consistency, especially on mobile. You can go very far with React Native approach (using native widgets), but there are limits. There are many failed attempts to draw UI oneself. But ultimately, it is because development cost (you need to implement a lot of widgets, supporting new OS capabilities in on-going basis). If Google can support these development cost, it can be done. Accessibility issues can be solved for these toolkits. OS often exposed some kind of the API to achieve that. For web, you certainly can have hidden elements to support accessibility. Again, it is just a matter of development cost. As you said, nobody should seriously mistake Flutter app with semantic web. Most of the SPA online will break if you style CSS differently or disable Javascript, this is just the world we live in. The missing of semantic information for Flutter app should be treated as the generic accessibility problem, not some resistance to the semantic web vision.