I never said 'exactly'. I said 'similar'. Interest rates are a signal, but since the underlying micro economy is constantly changing, the derived macro economy is also changing. Therefore, the (equilibrium) interest rate is constantly changing and always a bit off.

You are right. Some interest rates change; others don't. For instance, you can choose between a fixed and variable annuity IRA accounts. I didn't mean to imply that all interest rates change.