But in the pilot wave theory, there is only one actual state of the universe, though that state propogates with explicitly non-local interactions. That state in

But in the pilot wave theory, there is only one actual state of the universe, though that state propogates with explicitly non-local interactions. That state includes hidden variables, namely particle positions, velocities, and IIRC quantum phases. It may take exponential time to simulate the distribution of measured results given only the measurable inputs (which is what we do when we model experiments), but the universe itself knows the hidden variables and so can calculate the next state quite efficiently. So ontologically, a non-local hidden variables theory is much simpler than many worlds. Copenhagen is unworkable ontollogically; it assumes some distinction between normal interactions and "measurements" which are poorly defined.