If you are worried about why I can't share my screen on facetime then you don’t have to worry anymore because we are here to help you. All you need to do is follow some simple steps which are given below:
1 Open your device and go to the setting
2 Now turn on Facetime
3 Now open Facetime application on your device
4 Now call anyone from your contact list
5 When the call is connected then Tap on ‘Share Content’ icon
6 Now tap on ‘Share My Screen’ Option