While the requirement is there, often it falls through the cracks. A recent example is the wrong mapping of the Starliner thrusters. This wasn’t found until the simulator changed due to brownouts after it was already in orbit. Just by luck, the new simulator was of sufficient fidelity to catch the mapping error.

Had 1) they not missed the correct orbit due to a different issue and 2) not had to switch simulators it could have potentially collided with the space station.

So yes, the requirements are there but often not followed but luck was on our side