Before electric turn signals there were the mechanical arms complete with reflectors in them -- at least on trucks. They were actuated by pulling a cord inside the cab and the arm extended horizontally from right or left --depending on which way you intended to turn. To cancel you pulled down a little further and the signal arm retracted. I drove an old International KB (7?) tractor for Samson Truck line in Mtn. Home Idaho about 1959 that had the mechanical turn signal arm. After that era electric turn signals with a lighted arrow in a round lens were often mounted on top of the front fenders but you had to remember to cancel. No self-canceling signals in those days but it was a mighty leap forward from the old mechanical arms.
They are orange in Europe. This makes no difference. You can t fix stupidity just by changing the color of a bulb
Not sure about the law requiring turn signals, but in South Carolina until about 1960, in order to pass the drivers test, you were required to drive a full size, straight drive car and use hand signals, even tho most vehicles had turn signals. The test included a stop on a hill, and a pull off with out rolling back. At the age of 16, I passed the test to drive a state school buss, don't think I would want my GC to ride on a school buss driven by a 16 year old now.
My 39 Buick had them only on the trunk as factoty and the switch was on the collum shifter (non self canceling). My 40 had them all around, factory installed on the right side of the collum, self canceling. Iceman