Pappenheimer: You misunderstood. Physics does not claim that there are causes we cannot observe. It claims that there are no causes at all for the mentioned effects. This is in fact one of the most famous and surprising statements of quantum mechanics. If there were some unobservable causes, the experiments to Bell's theorem had a different outcome. So we know that there aren't such causes.

But you're right that on a higher level we normally have a defined cause -> effect relationship. Normally, but not always. Events on an atomic level can influence biological effects, for instance in the notorious Schrödinger's Cat experiment.

Quantum effects lacking causes are, by the way, already industrially exploited. For instance for creating true random generators that generate an unpredictable random sequence. Or in the future, for quantum cryptography.