You must drive a car.
Drive a big truck and people won't dare give you the finger, the look, or anything else out of fear; when you don't use the turn signal.
More like "Hey, no problem. I'm cool. Keep on rolling, big guy. Heck, I'm GLAD you failed to let me know you were turning."
I'm actually one of the turd heads you are ranting about. I rarely use a turn signal. Not sure why. Just habit.
At normal intersections and turns, it's no big deal. But I do get ticked when someone is turning off onto some obscure road and fail to put on a turn signal. They are pushing their luck of getting a Dodge Ram with Lee Ann Womak blasting crammed up their trunk.