Almost, it should how much improvement the AI needs to avoid collisions a human driver did avoid. The AI might avoid collisions that the human didn't. In other

Almost, it should how much improvement the AI needs to avoid collisions a human driver did avoid. The AI might avoid collisions that the human didn't. In other words, you need 0 simulated collisions to be strictly better than a human driver (in the same setting). Not ~equal with sometimes better and sometimes worse.