Explore a conference talk from TQC 2023 that delves into extending the definition of entropy from classical and quantum sources to operational probabilistic theories. Learn how information content transitions from classical bits to quantum qubits, and examine the challenges in generalizing entropy measures. Discover insights into subadditivity properties, state purity measurements, and why proposed entropy generalizations fail to satisfy a generalized noiseless coding theorem through analysis of a bilocal classical theory model. Presented at the 18th Conference on the Theory of Quantum Computation, Communication and Cryptography at the University of Aveiro, the talk progresses through compression tasks, theoretical frameworks, key problems, and a compelling counterexample before concluding with an interactive Q&A session.