Thats the thing - with an unauditable black box like iOS you have to trust the vendor that it actually does what they say. If they suddenly start to break you

Thats the thing - with an unauditable black box like iOS you have to trust the vendor that it actually does what they say. If they suddenly start to break you trust - who knows what they will push to that black box next time ? You have no way to tell or prevent that, other than leaving the whole platform altogether.