Ask HN: Why is there no software for generating cross-platform native UI code?

HTML + CSS, iOS and Android all are complete design systems. Any UI that we design can be developed for these platforms.

Forgive my possibly naive understanding of mobile UI. Why is there no software/ service that allows us to develop on one platform and automatically transpiles into the other platforms?

Is it because it is extremely complex or because developing the UI is not the most time-consuming element of cross-platform development or both?

A form field for web - <input ..../>

is <EditText ..../> for Android

and <UITextInput ..../> for iOS