Insler said many systems on an airplane work in the background without the pilot’s knowledge
perhaps he should have said many non-safety systems work.. like do you know how the toilet flush mechanism works, how the cabin entertainment works etc? Other than knowing what circuit breakers to pull to isolate the system, I don't believe pilots need to know about a lot of the above other than a general overview. For any flying, safety system then yes the Pilot needs to know everything there is to know about the mechanics and electronics and interactions and design decisions made.
The job is more system engineer than flyer these days..
G