Comment by riknos314

No simulation is perfect, so ideally you have a feedback look constantly looking at new real-world data as it comes in and finding where the simulation has errors, and updating the simulation to improve the correlation between the simulation and the real world over time.

My guess is they did have flooded street sims but the correlation was much lower than expected, or the details of the situation being simulated (lighting, building locations, how dirty the water is, ...) were sufficiently different from the situation that was encountered that the sim based training didn't generalize to the new context.