Hi Dream Land:
What you suggest happens is not entirely true.
The regulatory authority in the US (the FAA) does not authorize circling approaches in a simulator that has not been evaluated to be able to do so WHILE complying with the regulatory requirement I quoted above (...must maintain an identifiable portion of the airport in sight throughout the maneuver); AND the maneuver demonstrated must be flown where there is at least a 90 degree difference from the approach to the landing runway - (i.e., Memphis Tennessee approach to Rnwy 27 circle to land on Rnwy 18R) - there are several such runway combinations at US airports. Once successfully evaluated, the simulator may then be approved for circling approaches; but not until then.