I would argue that it's impossible to simulate real-world conditions for a task as complex as driving. There are too many edge cases and different combinations

I would argue that it's impossible to simulate real-world conditions for a task as complex as driving. There are too many edge cases and different combinations of environmental factors, many of which involve the inherent unpredictability of other drivers. I would assume medicines have similar or higher levels of complexity involved. However, the medicine analogy is poor. We often release medicines for use even when they have incredibly harmful side-effects. We do the testing to quantify and understand those side-effects, not prove that each medicine does exactly what it should with no side effects.