By majority it's 100%, physics exists and the time required to maneuver in being capable of turning or lane changing is plenty to clearly signal what it will do. The reality is that if you need turn signals you are bad at driving and should not drive. Most humans are not capable and cars should not be how the majority of people get around.
I'm saying that if you need signals to reduce the risk of crashing you shouldn't drive, which is probably 98% of humans. That is the vast majority of people should drive.
Okay, well good luck convincing people not to go to work or the supermarket in places without robust public transportation unless they have a bicycle and it isn't dangerously cold or dangerously hot outside.