An emergency like a storm and the internet goes out. Not an emergency like oh wow we are about to get in a wreck.If you have to be ready to take over in an emergency then you might as well be driving. If you’re not 100% ready then you’ll be no use if something goes wrong. So it seems to me there’s no point (from a user’s perspective) of semi-autonomous (there’s certainly a point from a developer’s perspective). Go full-autonomous or go home.