The majority of Google’s revenue is directly tied to their Ads platform.
Their mobile app is written in Flutter and the web interface is written in Dart (not flutter as flutter web support is like around a year old).
Facebook uses React on the web and abandoned react native on mobile.
Both are responsible for billions of dollars but only one passed the test.
That's not true, FB very much still uses RN on mobile.
The Ads Manager app is written in React Native.
The Instagram app is written in React Native.
The entire FB app is not written in React Native yet, but overtime I'd expect more things to be.
The statement that FB "abandoned react native on mobile" is demonstrably false.
Second, they serve different purposes. Litho will be used for FB scale optimization of certain intensive views. React Native is used for fast developer productivity. I'd wager that RN will be used in most places and Litho is used in hot spots sparingly.
Someone currently on the Instagram team can correct me if I'm wrong.