Mercedes-Benz debuts turquoise exterior lights to indicate the car is self-driving | A visual indicator for other drivers

Same reason at this point as "Student Driver" bumper stickers - so you know it's inexperienced and may behave weirdly, so maybe keep a bit more distance than usual or something.

So you don't call the cops when you overtake them and see then eating a bowl of cereal, jerking it, while watching Flinstones.

That's what I thought. I can only imagine idiots will see it and try fuck with it. Anyone else be like, "Okay... So just keep doing what I'm currently doing."

It's marketing, if anything.

My theory on Audi bringing out animated indicators was that they were quickly getting a damaging reputation of Audi drivers not using indicators; a reputation their competitor BMW is negatively married to. To prevent this, they appealed to making them unique and special, no one else had them, so the drivers would want to use them. Thus actively mitigating brand damage on BMW levels.

I would love to have an indicator for adaptive cruise control because the way it only reacts to the car right in front of you rather aggressively means it causes shockwave traffic jams unless the human driver behind you keeps enough distance.