You are also thinking Barber Pole, Sweeney Todd, .. Il Barbiere di Siviglia, etc, the truth is not far from Mr Sweeney Todd after all...
The look of the barber pole is linked to bloodletting, with red representing blood and white representing the bandages used to stem the bleeding. The pole itself is said to symbolize the stick that a patient squeezed to make the veins in his arm stand out more prominently for the procedure. In Europe, barber poles traditionally are red and white, while in America, the poles are red, white and blue. One theory holds that blue is symbolic of the veins cut during bloodletting, while another interpretation suggests blue was added to the pole as a show of patriotism and a nod to the nation’s flag.
Portland, Oregon 2019.