How were other teams ever going to pick up on exactly what the Ferrari fuel system was doing that got banned? Drawings can only go so far.
Ferrari went backwards after the confidential agreement.
Compare that with what happened to BAR where they found the extra fuel tank. Yes, that was far more blatant but teams have learnt to be more subtle.
It is alleged RB drawings show the RB has a “lever” to adjust the front wing but it’s supposed to not be accessible when the car is fully built. All they have to do is find a way to make it accessible in the garage between qually and the race. Very hard for teams to verify .