Does anyone know what a red turn arrow means?

Welcome to my little rant. Does anyone know what a red turn arrow is? It’s literally a red light. Why do people think it’s okay to just casually enter an intersection to do a u-turn when the light is red? Then they act like everyone else is the problem. Probably the same people who drive with their high beams on driving slow I. The left lane of I had to guess. Thank you for listening/reading.