You're confusing 'causality is the same for everyone' with 'causality exists'. Hume already showed nearly three centuries ago that causality - as we interpret it - is purely a mental construct, and if we assume humans are equipped with mostly the same mental faculties, it's reasonable to assume 'causality' is the same for everyone. This leaves completely open the possibility of whether causality actually exists outside of our mental constructs (quantum mechanics would say it both does and doesn't at the same time, only after it's observed does a causal relation either exist or not), and if it does, whether our mental constructs are reflections of the actual causal processes or causal interactions, whether our mental constructs and actual causality function in different ways (our mental constructs could require counterfactual dependence, but perhaps actual causality doesn't). These questions concern metaphysicians to this day. To return to the apple: it's only cut if you choose a frame of reference to observe it.