A pre-flight check doesn’t need knowledge of every part, it needs to show that all moving parts are in order, fluids at proper levels, etc..

Do they disassemble the body of the plane to expose every internal mechanism? Do they pull out any electronics to see if there is anything behind them that shouldn’t be? Does every pilot do the necessary overhauls and engine maintenance on their specific plane or do they have the mechanic at the airport/air field do the majority of it for them? Do they know every single part on their plane and know for a fact that it was the one on it the last thing they flew the plane?

I call bullshit.