This would be very helpful anytime I'm driving in the left lane only to realize that the person in front of me has decided to make an illegal left turn at the coming intersection.

Or anytime I'm in a bike lane and the car to my left is slowing down inexplicably

Thank you for your helpful PSA, OP. Car technology is changing so rapidly these days with all the fancy computers etc., so it's helpful to have an explainer for one of these great new safety features