I don't think we specifically need a reaction-speed test for Level 2 driving systems, but maybe we could for driving in general. The pernicious combination tha

I don't think we specifically need a reaction-speed test for Level 2 driving systems, but maybe we could for driving in general. The pernicious combination that makes L2 unsafe is that it encourages the driver to let their focus wander, and then unexpectedly demands that you have full attention. When 95% of your highway time requires almost no focus, your brain will naturally wander off and pay much less attention to the situation on the road. So when the 1-in-1000 dangerous situation occurs, you're less prepared to react to it than an unassisted driver would be. Edit to be more clear: A reaction-speed test measures your best-case reaction time, because you know it's coming. Normal driving situations test your "normal" reaction time. Situations under L2 test your worse-than-normal reaction time.