[red75prime]

The problem is that the larger subsystem includes an observer in a superposition of states of observing different measured values. And we never observe this. Copenhagen interpretation doesn't deal with this at all. It just states this empirical fact.

[thomasmg]

So if I understand correctly, you are saying the observer doesn't feel like he is in a superposition (multiple states at once). Sure: I agree that observers never experience being in a superposition.

But don't think that necessarily means we are in a Many-Worlds. I rather think that we don't have enough knowledge in this area. Assuming we live in a simulation, an alternative explanation would be, that unlikely branches are not further simulated to save energy. And in this case, superposition is just branch prediction :-)