That's not what I meant. Android and iOS already have their own widgets with accessibility features in place. iOS even better than Android. It took years for them to develop to where they are now.
Now Flutter is making its own widgets that look and handle like the corresponding native widgets. So they need to implement accessibility all over again in the same way that is already present on the platforms. Google is thus redoing all the work they already did in Android.
A lesson from modern software development is that software is developed incrementally and because accessibility is never high on those priority lists, it will lack in quality at first and take multiple iterations to get up to the same level as the native accessibility of the OS, if it even gets there in the first place.