I think in most cases, it’s beyond Django to enable this everywhere. It may disrupt production processes, especially where a web server process has signal handlers or logs need to be output in a particular format like JSON.
Django’s test runner does enable faulthandler by default, since this ticket. pytest does this too. I think that’s about as far as a framework can safely go.
Adding it to manage.py would indeed allow users to disable it if needed, but it would also be more code and concepts to expose beginners too, plus there’s an ongoing discussion to make a django command that could supersede manage.py files.
Anyway, I’d like to see what someone else thinks too.