My read on it is that - No, there does not need to be one ON the outside of the building - but does need to be visable and accessible from the motor equipment - in any application. In single family it would not need be visable to the occupant.... That said, if you you have GFCI protection prior to the disconnecting means - it could be under the skirt of a factory made tub - visable to the pool guy..... Or in some custom situation - visable from the pumps...
That said it most likely will be OUTSIDE - but not necessarily ON the building.