Take what i say with a grain of salt, (I’m not an iPhone hacker and I follow their work semi-loosely but from my understanding there are a number of available and documented tethered exploits. I wouldn’t doubt theres a number of untethered exploits that are waiting in Apple’s bug tracker system, or are simply too abusable for the general public to know about.

The are! It's just not an everyday occurrence - and so is worth much more - so most zero days end up in nation state hands.