It can be publicly auditable AND opaque. This is a very common misunderstanding. You have to trust something in the whole system, that trust might be reasonably placed in cryptographic primitives that assure anonymity and privacy as well as assuring no inflated coins are created, primitives which have been reviewed and audited, over and over again. From compilers to central processing units to hash functions, you are already trusting a LOT in Bitcoin. #monero adds a little bit to that gigantic pile or complexity. All of this is explained in

Monero Inflation Checker