Like incompressible fluids, electricity is hard to reason about because we work in a limit that does not obey local causality.
The entire system must be solved simultaneously, and there is not a well defined "input" or "output". This can be seen from the fact that when we analyze a circuit we also include the model the power source and the load.
The combination of non-locality and complex boundary conditions makes it hard to apply ordinary intuition. We would like to say that the power source "does something" to the circuit but causality actually runs both ways. E.g. if we have a constant voltage source, then the circuit will determine how much current flows through the source. If we have a constant resistance load, then the load will determine how much power the circuit applies to it.
The entire system must be solved simultaneously, and there is not a well defined "input" or "output". This can be seen from the fact that when we analyze a circuit we also include the model the power source and the load.
The combination of non-locality and complex boundary conditions makes it hard to apply ordinary intuition. We would like to say that the power source "does something" to the circuit but causality actually runs both ways. E.g. if we have a constant voltage source, then the circuit will determine how much current flows through the source. If we have a constant resistance load, then the load will determine how much power the circuit applies to it.