Most street legal vehicles utilize a combination of three colored lights: white for headlights and reverse lights, red for tail and brake lights, and orange for blinkers....
Mercedes-Benz debuts turquoise exterior lights to indicate the car is self-driving | A visual indicator for other drivers::undefined
My aftermarket Openpilot setup does this with a camera pointed at the driver. I'm good about paying attention but apparently if it alerts too many times that you're distracted it will disable itself until you restart the car.
The reason for these lights is that Mercedes has Level 3 autonomy, so the car can self drive without the driver taking attention - for example here in Germany it is illegal (and there are photo traps) to use your phone on while driving. The lights are a solution to the exemption that you are allowed to use your phone while your car is on Level 3 autonomy.
On level 3 you need to be able to take over again within 30 seconds after the car actively asks you to do so.
The level 3 autonomy is under extremely limited circumstances, which are basically on the bighway under 40 mph. These are basically the safest possible conditions to have level 3, and it is the right place to start.
I'm not against them starting it. I'm against them telling the drivers they can take their hands off the wheel, their feet off the pedal, and watch media on the center console. We aren't there yet.